iOS and Cross-Platform Development

Based heavily on Mac OS X
Closed source
- Tools, deployment, app ecosystem controlled by Apple
Apps can only be installed from the App Store
- Cryptographically signed
- Apple runs App Store
- Approves all apps available from it

Written in Objective-C & Swift
- An extension of C to add support for objects
- Using the Cocoa Touch UI framework
- Can also use C/C++ libraries
- Compiles to native code via LLVM (not interpreted (JIT) as on Android)

Model View Controller Design Pattern

UI Application Object: manages event loop & high-level app behaviour

Application Delegate: Handles app initialisation and state transitions

Data Objects: Store data for the app (images, database, etc.)

Document: Manage data objects

View Controller: Manages the presentation of the app on the screen, loads views, shows views, rotates views, etc.

UI Window: Coordinates the presentation of one or more views on a screen

Views & UI objects: Draw content, buttons, etc.

Apps are sandboxed; inter-app communication is used to pass data
Only one application in the foreground / visible at once
A main loop processes events for the application
- Xcode creates the main function
App can be in a number of significant states
- Active: foreground
- Inactive: foreground but interrupted
- Background: same as services in Android
- Suspended: main loop no longer running; remains in memory but is potentially killed by the operating system

Pre-moderation
- Apple checks all applications in advance manually
- Versus Android: publish and then revoke
A long list of guidelines as to what is appropriate

Cross-platform