iOS关闭App带动画退出

iOS代码退出程序一般直接调用exit(0); ，但是视觉上看起来像闪退，借鉴网上别人的代码，一个向下切出退出程序的方法，代码如下：

 

- ( void )exitApplication {
    AppDelegate *app = [UIApplication sharedApplication].delegate;
    UIWindow *window = app.window;

    [UIView animateWithDuration: 1 .0f animations:^{
        window.alpha = 0 ;
        window.frame = CGRectMake( 0 , window.bounds.size.width, 0 , 0 );
    } completion:^(BOOL finished) {
        exit( 0 );
    }];

}