The ultimate guide to building a mobile app
Got a great idea for an app? Need a new way to grow your business? We tell you everything you need to know about building a mobile app in 2020.
The iPad is a tablet designed and developed by Apple that introduces a world of possibilities in terms of technology and performance. An iPad Developer specializes in the things that make the iPad great, from building mobile apps to developing tools that unlock its potential.
These developers are skilled individuals with an understanding of both design and programming, resulting in features and functionality that is tailored for any need or requirement. As a professional iPad developer, they have the knowledge and skill-set to design, develop, and implement your vision to produce tools and applications that work optimally with the iPad.
Here's some projects that our expert iPad Developers made real:
At Freelancer.com, we experience firsthand how iPad Developers can propel projects forward by taking advantage of the tablet’s unique capabilities. We invite you to post a project on Freelancer.com and hire an accessible yet professional iPad Developer at an accessible price. Our experts are equipped with the latest tools to bring your ideas to life – so why not give it a try?
From 92,084 reviews, clients rate our iPad Developers 4.84 out of 5 stars.The iPad is a tablet designed and developed by Apple that introduces a world of possibilities in terms of technology and performance. An iPad Developer specializes in the things that make the iPad great, from building mobile apps to developing tools that unlock its potential.
These developers are skilled individuals with an understanding of both design and programming, resulting in features and functionality that is tailored for any need or requirement. As a professional iPad developer, they have the knowledge and skill-set to design, develop, and implement your vision to produce tools and applications that work optimally with the iPad.
Here's some projects that our expert iPad Developers made real:
At Freelancer.com, we experience firsthand how iPad Developers can propel projects forward by taking advantage of the tablet’s unique capabilities. We invite you to post a project on Freelancer.com and hire an accessible yet professional iPad Developer at an accessible price. Our experts are equipped with the latest tools to bring your ideas to life – so why not give it a try?
From 92,084 reviews, clients rate our iPad Developers 4.84 out of 5 stars.More details: What platform should the app be developed for? Both iOS and Android What additional features would you like the app to have? Push notifications for new job matches, In-app messaging with employers How should the job roles be categorized for filtering? By Industry, job title and location
I'm in need of an experienced mobile app developer to help me bring a cross-platform productivity mobile app to life. Key Requirements: - Design and develop a mobile app compatible with both iOS and Android - Focus on enhancing productivity through user-friendly interface and features for streamlining the procurement in my company - Prior experience in creating cross-platform mobile apps is a plus Ideal Skills: - Proficient in mobile app development languages such as Swift, Java, Kotlin, Dart - Experience with cross-platform development tools like Flutter, React Native, or Xamarin - Strong understanding of UX/UI principles for productivity-focused apps - Excellent problem-solving skills and attention to detail. Freelancers with a portfolio demonstrating previous work on producti...
I'm looking for a skilled mobile app developer to create a task management app for both Android and iOS. The app's primary purpose is to boost productivity by helping users manage their tasks efficiently. Key Features: - Basic task management functionalities: Adding, editing, deleting tasks - Task assignments: Users should be able to delegate tasks to others - Due date reminders: The app should notify users of upcoming deadlines - Progress tracking: Users need to see their progress on tasks Ideal Skills: - Proficiency in Android and iOS app development - Experience in creating productivity apps - Strong understanding of task management features - Ability to implement user-friendly interfaces - Knowledge of integrating reminder systems and progress tracking features Please sha...
I need assistance with deleting all my text messages (SMS) from my old iPhone to my new one. I want to keep my new phone clean and free of clutter. Ideal Skills: - iPhone expert - Data management - Attention to detail
I'm in need of a developer who can assist me with creating a Recipe Book App using Flutter and Firebase. This app's primary purpose is to store personal family recipes. Key Features: - User-friendly interface for easy recipe input and navigation. - Search functionality to quickly find specific recipes. - Integration of an ingredient list and shopping list for convenient grocery planning. - A recipe rating and review system for personalized feedback and recipe improvement. Ideal Skills: - Proficient in Flutter and Firebase. - Experience in developing similar apps. - Good understanding of UI/UX design principles for app development. This project is a perfect fit for someone who loves cooking and understands the importance of family recipes. If you can provide a demo of a simil...
My app has been taken down from the Google Play Store due to inactive downloads. I am looking for a professional who can restore the app to the store and provide ongoing maintenance. This is what I need: - General projects as content requires updates from time to time. - Performance optimization: The app's performance needs to be enhanced to ensure a smooth user experience and to increase the chances of attracting more downloads. I'm uncertain about the necessity of a full code review. I would appreciate your advice on this matter. Ideally, you would have: - Prior experience in app restoration and maintenance. - Strong technical skills to handle bug fixes and performance issues. - Proven track record of optimizing app performance. - Ability to provide insightful advice on code...
I need a mobile application to connect Casting Professionals with Actors. The app should primarily facilitate scheduling auditions, messaging and notifications, and managing profiles and portfolios. 
OBJECTIVE To develop a mobile application that streamlines communication between Casting Professionals and Actors. The app will facilitate the management of casting calls, enable real-time communication, and provide a user-friendly interface for both parties, similar to popular social media platforms like Instagram and BeReal.

App Functionality Overview Features for Actors 1. Profile Creation and Management: Detailed Profiles: Actors can create profiles that include personal information, headshots, demo reels, skills, experience, and contact inf...
I am looking for app for recruitment consultant. We have got three type of users here one user is typically a job seeker other two users are like employers and also they will be providing business opportunities. Since all these three users are into the same industry I need connection option for all these uses. for example user can send a friend or connection request to the other user, if he or she knows very well he will accept the connection, so the connection keeps expanding and this should be visible in the app also which user has got more of connections. here we don't provide them any kind of chat option. it is typically you post the job opportunity & business opportunity. And job seekers also put their requirement if the requirement and opportunity matches user should ge...
I'm looking for a seasoned app developer who can design, develop, and launch an E-commerce app for both Android and iOS. The app will primarily sell digital products and needs to support in-app purchases. Key Requirements: - In-app Purchases: The app should have a seamless and secure system for in-app purchases. - E-commerce Expertise: Prior experience in developing E-commerce apps will be a significant advantage. - Cross-Platform Proficiency: The developer should be well-versed in both Android and iOS app development. - Digital Products Knowledge: Familiarity with the sale and distribution of digital products is preferred. Please provide examples of your past work in your bid, specifically any E-commerce apps you've developed. I look forward to collaborating with a professiona...
I'm seeking a part-time iOS developer with specific experience working on DoorDash's delivery platform. The focus will be on the driver interface and backend integration. Key Responsibilities: - Enhancing and integrating the driver interface on a DoorDash-like platform - Working on backend integrations using existing APIs and documentation - To complete the our APP which is 90% completed. Ideal Candidate: - Proven experience with iOS development - Specific experience with DoorDash's platform is a plus - Strong understanding and practical experience with driver interfaces - Skilled in backend integration - Able to work part-time and deliver quality work Compensation 3 hours a day 15-20 hours a week @$6.00 per hour
I'm a pharmacy graduate looking to develop a mobile app that will initially focus on delivering medicines within a specific city, with the potential to expand to other basic medical supplies in the future. I need an experienced app developer to bring this vision to life. - The app must allow for user profile creation, ensuring the authenticity of each user. - It should have a comprehensive data collection process for user details and order specifics. - The app needs to incorporate a seamless order-taking system, display prices, confirm orders, manage deliveries, and gather user feedback. - Compliance with health regulations and legal standards in my city is essential. - The ability to scale the app for future expansion to other medical products is a requirement. The ideal freelancer ...
I need someone to create a simple mac application that can initiate phone calls using Iphone (like facetime) Just need a simple dialer interface that can also access contacts.
I'm looking for a talented developer to create a stock trading app for Android. This app should be able to provide real-time quotes, manage portfolios, send trading alerts, and execute hedge trades based on specific parameters. Key Features: - Real-time Quotes: The app should be able to deliver live stock prices. - Portfolio Management: Users should be able to track their investments and assess their performance. - Trading Alerts: The app should notify users of significant market changes or personal stock updates. - Hedge Trades: The app should be able to execute hedge trades based on pre-set parameters. Ideal Skills: - Proficient in Android app development - Experienced in creating trading apps - Knowledgeable about stock market mechanics - Ability to implement real-time data proc...
More details: Is this project for business or personal use? Personal What information should successful freelancers include in their application? Experience How soon do you need your project completed? ASAP
I'm seeking a talented developer to create an AI-powered mobile app for a tuition centre. The app's key objective is to bolster communication between teachers and parents. Key features of the app: - A robust messaging system that allows seamless communication between teachers and parents. - A progress tracking and reporting feature that keeps parents updated on their child's academic advancement. Ideal skills for this project include: - Expertise in mobile app development, particularly for AI-integrated applications. - Prior experience in developing educational apps would be a significant advantage. - Strong understanding of creating user-friendly interfaces, as the primary users of the app will be teachers communicating with parents.
I'm looking for an experienced app developer who can create a cross-platform (Android and iOS) app similar to RealtyCalendar with the following key features: - Booking Management: The core of the app is efficient booking management. - Calendar Integration: Seamless integration with user calendars is essential. - Automated Reminders: The app should send automated reminders to users about their bookings. - Booking History: Users should be able to access their complete booking history. Additionally, the app must include a simple and secure Email login for user authentication. Ideal skills for the job include: - Proficiency in cross-platform app development. - Experience with implementing booking management systems. - Knowledge in integrating calendar functionalities. - Ability to cr...
I'm looking for a skilled iOS developer to create a simple but effective quality inspection app. The app should allow an operator to: - Input their ID - Choose between 2 product versions - Scan a QR code (serial number) - Take pictures, save them and create the log with Timestamp, Operator Nr., Serial Nr. etc. The app needs to sync data to iCloud after each inspection. It should be user-friendly and efficient, helping to streamline the inspection process. Ideal candidates should have prior experience in developing iOS apps or similar projects. Familiarity with QR code scanning and iCloud integration is a must.
I'm seeking a skilled developer to create an interactive stock trading app for both iOS and Android. The app should allow users to trade with virtual money, simulating a real-life trading environment, and learning about the stock market in real-time. Key Features: - The app must provide real-time market data to mimic actual trading conditions. Ideal Skills and Experience: - Proficiency in cross-platform mobile app development, preferably using frameworks like React Native or Flutter. - Prior experience in creating financial or trading apps is a plus. - Strong understanding of stock market mechanics. - Skills in integrating live data feeds into mobile applications. - Knowledge of user-friendly UI/UX design principles.
I'm looking for a Flutter developer to update my e-commerce app. In my app, only logged-in users can access the home screen and products. So, I want to implement a "skip login" button for non-logged-in users to access the home screen and products. However, these users should not be able to purchase items without logging in. Other requirements:- - Update the apps to target the latest API level. -Provide source code and aab file for Play Store upload. -Upload the IPO file to my Apple developer account with the necessary screenshots.
I'm looking for a business partner in my software development agency. The agency is based in either Australia or New Zealand, so I encourage only local partners to apply.
I'm looking to improve my mobile app, SMATCHME, a tennis social network. Key Responsibilities: - Integrate new match types into the app: specifically, doubles matches, as well as the sports Padel and Pickleball. - Today the app supports only tennis and italian courts, while we would extend to USA Ideal Skills: - Proficiency in mobile app development, particularly with social networking features. - Experience with implementing various match types in a sports app. - Knowledge or passion for tennis, Padel, and Pickleball is a plus. - knowledge of native IOS and Android mobile development
I have an already developed iOS app that I'm looking to publish on TestFlight. I need help with uploading the build and managing tester groups. Ideal Skills and Experience: - Familiarity with TestFlight and its processes - Experience in managing TestFlight tester groups - Knowledge in uploading builds to TestFlight
My iOS app has been crashing unexpectedly. I have not seen this issue on the Android version. I need help diagnosing and fixing the problem. Ideal skills and experience for the job: - Extensive iOS app debugging experience - Strong understanding of app development - Problem-solving skills - Attention to detail
I'm looking for a versatile mobile application for both iOS and Android. This app should connect users to various barber and spa shops, featuring: - An Online Booking System: Customers should be able to book appointments seamlessly. - Payment Processing: The app should integrate a secure and user-friendly payment gateway. - User Reviews and Ratings: A section for feedback and ratings to ensure transparency and quality control. In addition, there's a necessity for shop owners to manage their services and schedules within the app. This would require a separate, intuitive interface for them. Ideal candidates would possess: - Proficient mobile app development skills, particularly for iOS and Android. - Previous experience in building service-oriented apps. - Knowledge of integrati...
I need a reliable third-party app that allows me to access my Android phone using my iPhone. The Android phone will remain stationary while I, with my iPhone, will be on the move. I require full control over the Android device, inclusive of file transfers. Ideal Skills: - Expertise in identifying and recommending effective third-party applications for remote control. - Experience with Android and iPhone compatibility and connectivity issues. - Understanding of file transfer protocols between different operating systems. Please provide your proposal if you have the necessary skills and experience to assist with this project.
I have existing apps that need updating. I require a skilled iOS and Android developer who can: - Show a splash screen until the app page is loaded - Send order notifications The notifications will include order confirmation, order shipped, and order delivered. Please note that I do not want to work with an agency. The ideal candidate should have experience with both iOS and Android app development and must be able to submit the updated apps to the App Store and Play Store.
I'm looking for a skilled app developer to create a motorcycle taxi booking application called **Ride**, similar to Heetch. The app's primary focus is to facilitate motorcycle taxi bookings, providing a seamless experience for both passengers and drivers. Key Features: - **Ride Booking**: The app should allow both instant ride bookings and scheduled rides. - **User Profiles**: There should be a profile system for both drivers and passengers, ensuring a smooth and personalized experience for all users. - **Driver Selection**: Passengers should be able to view driver profiles and choose the driver they prefer for their ride. - **Accept/Decline Rides**: Drivers should also have the option to view the passenger's profile and decide whether to accept or decline the ride based on...
I'm looking for a permanent solution to stop sending GIFs (but not other types of images) via text messages on my iPhone with operating system 18. The method should be using a third-party app, not the built-in iPhone settings or a custom software solution. Ideal skills and experience: - Proficient in iPhone operating systems and settings - Experience with third-party apps for iPhone - Understanding of iPhone's messaging system - Ability to implement permanent changes to device settings
I'm in need of a talented mobile app developer who can create an app called LostKeys. This app is designed to help users track their keys by uploading pictures of them. When keys are lost, users send the information to our team to recreate and send back a copy of the lost key. Key Features: - The app should be compatible with both iOS and Android platforms. - Users should be able to upload pictures of their keys in a specific manner. guide lines will be created so that key will line with an imaginary line of the phone screen - The app needs to incorporate robust security features including Two-factor authentication, Biometric login, and Encryption. - Create Profile 1. Name of Client + ke 2. Whether client wants to take picture of vehicle or house or office or filing cabinet etc cat...
I'm looking for a seasoned mobile app developer to create a food delivery application for both iOS and Android. The app should cater to both customers and restaurant/store owners, with essential features like user registration/login, order tracking, payment gateway integration, and a graphic catalogue. Key Features: - User registration/login: A secure and straightforward process for both customers and restaurant/store owners. - Order tracking: A real-time tracking system for customers to monitor their orders. - Payment gateway integration: A reliable and secure payment system. - Graphic catalogue: A visually appealing and easy-to-navigate catalogue displaying available food options. Ideal Skills and Experience: - Proficient in cross-platform mobile app development. - Prior experienc...
I need an IPA file for my Flutter app. I do not have a developer account, so I require someone who can create and deliver the IPA file to me. My app is currently designed for iOS only. Ideal Skills and Experience: - Proficiency in Flutter and iOS development - Experience in creating IPA files - Ability to deliver within a short timeframe. Please note that I have not yet specified the main purpose of the app or its specific features, so flexibility and understanding of basic Flutter functionalities are key. note :- I do not have a developer account
I'm seeking a developer to create a cross-platform (iOS and Android) social media application primarily focused on photo and video sharing. Key Features: - User Interaction: The app should enable users to 'like' and comment on posts, promoting engagement and community building. - Direct Messaging: An in-built messaging feature is a must, allowing users to communicate privately. - Stories: Incorporating a 'stories' feature, akin to those on Instagram or Snapchat, is essential. - Trend Tracking: The app should have a mechanism to highlight 'trending' posts and the 'most popular' content. Ideal Skills and Experience: - Proficiency in both iOS and Android app development. - Prior experience in developing social media apps or similar platforms will...
I'm in need of a skilled developer to create an Android and iOS application that provides geolocation-based product and service information. Key Features: - The app should inform users about certain products and services within a close radius. - Information displayed should include descriptions and prices of the products/services. - The app needs to present the nearby products and services both on a map and as a list. Ideal Skills: - Proficient in Android and iOS app development - Experience with geolocation technology - Skills in UI/UX design for both map and list interfaces - Understanding of e-commerce app development
I'm looking for a developer to create an app primarily focused on streamlining communication between actors, casting coordinators, and directors. The main aim of this app is to enhance the communication experience while facilitating the casting process. Key Features: - The app should have a reliable, user-friendly in-app messaging system. This will allow actors to communicate directly with casting coordinators and directors, helping to make the casting process more efficient. Primary User: - The primary users of this app will be actors. Therefore, the app should be designed with actors in mind, ensuring it's accessible and easy to navigate for all skill levels. Ideal Skills and Experience: - Proficiency in app development, particularly for user-centric platforms. - Experience ...
I'm seeking a professional with extensive experience in implementing AppMetrica for marketing campaign tracking, and a solid understanding of basic deep linking. My app operates on both iOS and Android platforms, and the primary focus of this project is optimising the app for effective user engagement driven by marketing initiatives. Key Responsibilities: - Integrate AppMetrica for tracking the effectiveness of marketing campaigns. - Implement basic deep linking for marketing purposes. Ideal Skills: - Proven experience with AppMetrica. - Strong understanding of deep linking. - iOS and Android app integration experience. Please provide examples of your previous work with AppMetrica and deep linking in your proposal.
I need a skilled professional to help me upload my Flutter-based utility app, which is designed for system monitoring, to the Apple Store. The task should be handled with utmost precision and care to ensure a successful submission. Key Requirements: - Proficiency in Flutter and Apple Store submission guidelines - Experience in uploading utility apps - Understanding of system monitoring applications Please note that I'm not entirely sure about the use of third-party APIs in the app, so the ideal candidate should also have the skills to troubleshoot any potential issues that may arise during the upload process.
I'm looking for a mobile app developer to create an interactive program featuring a crystal ball that delivers randomized fortunes from a pre-prepared list. The twist? Each fortune culminates in a party invitation. Key Features: - The app should be designed for mobile platforms. - Users will tap the screen to interact with the crystal ball and receive their fortunes. Since I haven't specified a particular programming language or framework, I'm open to suggestions. However, experience with Swift for iOS or Kotlin for Android would be a plus. It’s essential that you ensure the app is intuitive and engaging, as the aim is to make it a fun party tool.
I'm looking for a proficient app developer to create a driver app akin to Uber but for advertising. For both iOS and Android platforms. The app should primarily focus on tracking driver earnings, accepting campaigns, and driver detail information.
I'm looking for a skilled React Native developer to help me solve issue google login in mobile app. Ideal candidates should have substantial experience in mobile app development, particularly using React Native. Understanding of user authentication systems, in-app purchase processes, and push notifications is key. Your creativity and expertise will be instrumental in transforming this project into a successful app.
I'm currently in need of a skilled, native iOS developer to assist in creating a social media application centered around text-based posts and comments. Key Features: - The application will include notifications to keep users engaged and updated. - User authentication will be primarily via social media logins, so experience with integrating and working with social media APIs is a must. Ideal Candidate: - Proficient in native iOS development. - Previous experience with social media app development. - Strong skills in implementing and managing notifications systems. - Familiarity with social media login integration. I am looking for a professional who can bring this project to life with high-quality coding and an understanding of what makes a social media app successful.
I'm seeking a developer to create a cross-platform (iOS and Android) audiobook app for me. The app should be a straightforward audio player with essential features such as: - Play/Pause an audiobook - Skip forward/backward - Control volume - Display of the current playback time and total duration In addition, the app will require: - User authentication through email and password - A library or catalog for managing multiple audiobooks Ideal candidates for this project should have a solid background in mobile app development, specifically with audio players and user authentication systems. Experience in creating library or catalog systems within apps will be highly beneficial.
I'm in need of a talented mobile app developer who can create a health and wellness app. The app's primary function will be tracking workouts. Key Requirements: - The app should be compatible with both iOS and Android platforms. - Experience with fitness tracking applications is a plus. - A strong understanding of cross-platform mobile development is essential. - Ability to create a user-friendly interface is a must. Please include examples of similar projects you've worked on in your proposal.
I need a skilled app developer to create a Coaching App catered to both iOS and Android users. Key Features: - The app should incorporate functionality for live coaching sessions. Ideal Skills: - Proficiency in cross-platform mobile app development. - Experience in developing interactive, real-time applications. - Prior work in creating coaching or fitness apps would be a plus.
I'm looking for an experienced developer to create a face-swapping app for both iOS and Android. This app must be able to swap faces in real time using a live camera feed. Key Features: - Live camera feed swapping: The app should be able to swap faces during a live camera feed. - Facial filters: Users should be able to apply different facial filters. - Emotion recognition: The app should have the capability to recognize and display different emotions. - Makeup application: Users should be able to apply virtual makeup. Ideal Skills: - Cross-platform mobile app development - Real-time video processing - Augmented Reality (AR) experience - Familiarity with facial recognition technology Please provide examples of similar projects you've completed in your bid.
I need a professional Roku app developer who can add Arabic language support to my streaming videos Roku app. The app requires user authentication via MAC Address, so experience with secure login implementations is essential. Key Requirements: - Roku app development expertise - Proficiency in Arabic language integration - Experience with MAC Address user authentication - Knowledge of secure login systems - Ability to enhance user interface for language support
I'm in need of an experienced app developer to create a food-related app within a budget of INR 25,000. The primary purpose of the app will be to facilitate restaurant reviews. Key Features: - User Profiles: The app should allow users to create and manage their personal profiles, where they can track their activity, favorite restaurants, and more. - Messaging System: A built-in messaging system is essential, allowing users to communicate with each other, share their thoughts and opinions, and connect over their love for food. - Feed for Posts: Similar to social networking apps, there should be a feed where users can post their reviews, photos, and updates about their dining experiences. Ideal Skills and Experience: - Proficient in mobile app development, particularly in e-commerce ...
I'm looking for a multi-platform (iOS, Android, Web) money/debt management app. Key Features: - A repayment calculator that swiftly computes fast repayments, incorporating interest calculations and payment reminders. - Bill alerts in the form of push notifications. - Revenue generation through sponsored ads and referral ads. Ideal Skills and Experience: - Proficiency in cross-platform app development. - Experience in creating financial or budgeting apps. - Knowledge of integrating advertising into apps. - Skills in implementing push notifications.
I'm looking for a developer to create an app primarily focused on streamlining communication between actors, casting coordinators, and directors. The main aim of this app is to enhance the communication experience while facilitating the casting process. Key Features: - The app should have a reliable, user-friendly in-app messaging system. This will allow actors to communicate directly with casting coordinators and directors, helping to make the casting process more efficient. Primary User: - The primary users of this app will be actors. Therefore, the app should be designed with actors in mind, ensuring it's accessible and easy to navigate for all skill levels. Ideal Skills and Experience: - Proficiency in app development, particularly for user-centric platforms. - Experience ...
I'm in need of an experienced mobile app developer who can create a professional iOS e-commerce application for me. The app should primarily feature a comprehensive product catalog, showcasing all my products in an engaging and user-friendly manner. Key Features: - A seamless, intuitive product catalog - Secure, efficient Email and password user authentication Ideal Skills and Experience: - Proven experience with iOS app development, particularly in the e-commerce domain - Extensive knowledge in creating engaging product catalogues - Expertise in implementing secure user authentication processes - Excellent understanding of UI/UX principles for iOS Please share your portfolio with similar projects and your proposed timeline for this task.
We're seeking a highly skilled and motivated iPadOS developer to join our team in building a cutting-edge architectural design application. This app will empower architects with a unified and intuitive workflow for sketching, 2D drafting, simplified 3D modeling, and light BIM functionality, all within a single, user-friendly platform. Key Responsibilities: Develop a native iPadOS application using Swift and SwiftUI. Implement intuitive sketching tools with Apple Pencil support (PencilKit). Create a comprehensive 2D drafting module with precise drawing tools and support for various architectural drawing types. Develop a simplified 3D modeling environment with basic manipulation and visualization tools. Integrate light BIM features, including object data, schedules, and clash ...
Got a great idea for an app? Need a new way to grow your business? We tell you everything you need to know about building a mobile app in 2020.
Learn how to find and successfully work with a freelance Mobile App Developer for your next project.
Learn how to effectively work with freelance App Usability Analysts and optimize your app's usability. Maximize user engagement and conversion rates.