一、App生命周期

image

1、程序完成加载
application:didFinishLaunchingWithOptions: 

2、程序被激活
applicationDidBecomeActive:  

3、程序取消激活
applicationWillResignActive:   

4、程序进入后台，未来将进入suspended(挂起)状态
applicationDidEnterBackground: 

5、程序将要进入前台
applicationWillEnterForeground:  

6、内存警告,程序将要终止
applicationWillTerminate:  

AppDelegate 类实现文件

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    NSLog(@"--- %s ---",__func__);//__func__打印方法名
    return YES;
}

- (void)applicationWillResignActive:(UIApplication *)application {
    NSLog(@"--- %s ---",__func__);
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    NSLog(@"--- %s ---",__func__);
}

- (void)applicationWillEnterForeground:(UIApplication *)application {
    NSLog(@"--- %s ---",__func__);
}

- (void)applicationDidBecomeActive:(UIApplication *)application {
    NSLog(@"--- %s ---",__func__);
}

- (void)applicationDidReceiveMemoryWarning:(UIApplication *)application {
    NSLog(@"--- %s ---",__func__);
}

- (void)applicationWillTerminate:(UIApplication *)application {
    NSLog(@"--- %s ---",__func__);
}

打印调用顺序

启动程序

--- -[AppDelegate application:didFinishLaunchingWithOptions:] ---
--- -[AppDelegate applicationDidBecomeActive:] ---

按下Home键,程序进入后台

--- -[AppDelegate applicationWillResignActive:] ---
--- -[AppDelegate applicationDidEnterBackground:] ---

从后台，进入前台（重新进入程序）

--- -[AppDelegate applicationWillEnterForeground:] ---
--- -[AppDelegate applicationDidBecomeActive:] ---

选择 模拟器的Simulate Memory Warning

--- -[AppDelegate applicationDidReceiveMemoryWarning:] ---