iOS boot principle and application lifecycle

　　　iOS program startup principle and life cycle diagram:

　　The entrance to the iOS app is main.m

1 #import <UIKit/UIKit.h> 2  3 #import "WYSAppDelegate.h" 4  5 int main (int argc, char *    @aut Oreleasepool {8         return Uiapplicationmain (argc, argv, Nil, Nsstringfromclass ([Wysappdelegate class    }10 }

Where the Uiapplicationmain function takes four parameters, the first and second defaults, and the third argument must be the UIApplication class or its subclasses, if passed in as

Nil, then the default is the UIApplication class, the fourth proxy class that specifies the application, which must obey the Uiapplicationdelegate class

iOS boot principle and application lifecycle