About IOS 5

IOS 5 has many more features than IOS 4. A simple list is provided. 1. The cloud Synchronization Service is now available. 2. Added twitter. 3. The video and music are separated. 4. Push notification system. 5. added the wireless synchronization feature. In our development, Storyboard is a new concept provided by XCode4 and iOS5 to control the jump relationship between View controllers. You can understand it as a collection of previous Nib files. Because ARC is implemented during the compilation period, although it is the Objective-C feature released at the same time as iOS5.0, ARC actually supports iOS4. Only in iOS4, the weak keyword of ARC cannot be used. Because iOS4 is not required, we can replace the original keyword _ unsafe_unretained with weak. In this way, when this weak reference object is recycled, the weak pointer will be intelligently set to nil to prevent "wild pointer" from being generated. A large number of updates have been made to UIKit in iOS5. In addition to the UIStepper control, more custom interfaces are added for the previous control. We can easily define common controls such as UINavigationBar, UITabBar, and UIToolBar. CoreImage Apple introduced a new image class CIImage from iOS5. Compared with the previous UIImage class, CIImage is more suitable for image processing and image analysis. NSJSONSerialization: ios json.