iOS Coding Best Practices
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The document discusses iOS project structure and design patterns. It recommends using the Model-View-Controller (MVC) pattern to structure iOS projects. MVC separates an app's data model, user interface, and logic into three distinct components. The view handles display and user interaction, the controller manages changes and updates, and the model manages the data and business logic. CoreData is recommended for storing partial object graphs and including data concurrency. Key-Value Observing (KVO) allows objects to automatically notify observers of property value changes.
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iOS Coding Best Practices
- 2. Agenda • Project Structure • Design Patterns & Architecture • Storing Data • Coding Conventions
- 3. What main design pattern does Apple recommend for structuring your iOS projects?
- 4. Model-View-Controller Controller Update Coordination Changes Changes Update Model Data View Display
- 5. Default Project • Notice Classes is a catch-all default ‘’bucket’’ for code
- 6. MVC Formatted Project • Remove references • Create class folders in Finder • AppDelegate • Controllers • Helpers • Models • Drag into Xcode
- 7. According to Apple, should the model, view or controller be used to capture events?
- 8. Roles & Responsibilities • Model • Data/Algorithms/Networking • Most of your custom code lives here • View • Display/Event Capture/Visual Appeal • Don’t try to reinvent UIKit, use it • Controller • Coordination/Delegation/Odd Jobs • Transitions, Startup/Shutdown
- 9. Is this a good pattern & why? Update
- 10. Don’t cut out the controller! Avoid bi-directional messaging Reject Delay Validate Update • Network Access • Multiple Choices • Commit
- 11. Is this a good pattern & why?
- 12. Loose Coupling • Don’t skip MVC layers when messaging • Use controllers to coordinate messages • Don’t mix MVC roles in one object • Don’t gather too much work in one place • Don’t declare data in your view classes • Maintenance nightmare • You can display data in a view, just don’t store it
- 13. What are three of the design patterns used to communicate between the model, view & controller?
- 14. Communication Between Objects Target-Action Notification Delegation Reuse controls without Broadcast changes Control reuse subclassing “Yes” « When tapped, call this method » « Software keyboard “End Editing?” -setTarget:(id)target action:(SEL)action…about to appear! » UIKit (UIScrollView, ect) NSNotificationCenter Will/Did/Should -(void)scrollViewDidZoom:
- 15. How do you create a custom controller to split the screen in two parts?
- 16. You Don’t! Use the UISplitViewController • Don’t try to reinvent the wheel • UIKit has a lot of the base controls you need • Really question whether you need a custom control (and if it exists already) • Don’t misuse framework classes • ie Removing views from UIViewControllers • Don’t try to reinvent the way models, views & controllers talk to each other • Use delegates & notifications
- 17. Is this a good pattern & why? -(void)scrollViewDidScroll:(UIScrollView *)scrollView { if ([scrollView isKindOfClass:[UITableView class]}){ // do something } else { // use UIScrollView logic }
- 18. Class checks in delegate methods Code unmanagable over time - EverythingControllers Coding horror - iOS version of a GOTO Correct Approach on iPad Parcel out your controllers
- 19. MANDATORY: ALWAYS write/model out your iOS app design before coding! At first, I was like… But then, it was like… (in your brain) (in the repo)
- 20. Creating an MVC diagram of your project • Means you thought through the architecture • Means you know how the code will be organized physically & logically • Means you potentially avoided structural bugs • Easier to validate with the team • High quality projects & happy clients
- 22. What’s the optimal architecture for a Universal Application?
- 23. Optimal Universal App Architecture iPhone App iPad App UI Framework (Views & Controllers) Non-UI Framework (Networking & Models)
- 24. Photo Sharing Application Data from the model is in both the inspector and in the toolbar
- 25. MVC Structure Update Change Change Update
- 26. What are the six primary ways of storing data on iOS?
- 27. Six Model Options • Property Lists • Archives • Custom Files • Server/iCloud/APIs • SQLite • CoreData
- 28. According to Apple, what data should you store in your App Defaults/Preferences?
- 29. Don’t store data in settings! • Wrong tool for the job • App may get rejected • Settings Panel test • On/Off Advanced Features
- 30. What should you use for quick storage of strings, numbers, arrays, dictionaries, e ct?
- 31. Property Lists.
- 32. What should you use to store partial graphs?
- 33. CoreData • Modeling Tools • Simple save/restore • Queries • Data Protection • Ordered Relationships • UIManagedDocument • Partial Graphs • Undo • Incremental Stores • ect…
- 34. What should you use to include data with queue-based concurrency in your app?
- 35. CoreData again.
- 36. What should you use if you are dealing with a lot of legacy code or data, or you need to create an NSObject-based graph?
- 37. Custom Files.
- 38. When would you want to use a data archive?
- 39. For easily « serializing » and « deserializing » objects in a data file.
- 40. What are the two primary features of SQLite?
- 41. Provides Database functionality for iOS apps Supports Object Relational Mapping
- 42. Know Your Data Model Options • Property Lists • Archives • Custom Files • Server/iCloud/APIs • SQLite • CoreData
- 43. Coding Conventions • Brace style for if-else • Parenthesis style • Leading underscores • Code indenting • CapitalizationStyle (ie capitalization_style) Check out the Google iOS Style guide & Apple docs: http://google- styleguide.googlecode.com/svn/trunk/objcguide .xml
- 44. What is KVO?
- 45. Key-Value Observing (KVO) • Requires your code to be compliant • Follow style guide • Instrument your own notifications • Automatic Change Notifications for your objects