- (void)initBlock{

    //延时的方法

    //1:GCD延时 此方式在能够在參数中选择运行的线程。

是一种非堵塞的运行方式，没有找到取消运行的方法。

    double delay1=2.0;//设置延时时间

    dispatch_time_t popTime=dispatch_time(DISPATCH_TIME_NOW, delay1 * NSEC_PER_SEC);

    dispatch_after(popTime, dispatch_get_main_queue(), ^{

        UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"" message:@"GCD延时" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:@"取消", nil];

        [alert show];

    });

    //2:NSTimer延时,此方式要求必须在主线程中运行。否则无效。是一种非堵塞的运行方式，能够通过NSTimer类的- (void)invalidate;取消运行。

    [NSTimer scheduledTimerWithTimeInterval:8.0f target:self selector:@selector(delayMethod2) userInfo:nil repeats:NO];

    //3:PerformSelector延时

    [self performSelector:@selector(delayMethod) withObject:nil afterDelay:5.0f];

    //4:NSThread 延时

    [NSThread sleepForTimeInterval:11.0f];

    [self delayMethod3];

}

- (void)delayMethod{

    UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"" message:@"PerformSelector延时" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:@"取消", nil];

    [alert show];

}

- (void)delayMethod2{

    UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"" message:@"NSTimer延时" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:@"取消", nil];

    [alert show];

}

- (void)delayMethod3{

    UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"" message:@"NSThread延时" delegate:self cancelButtonTitle:@"确定" otherButtonTitles:@"取消", nil];

    [alert show];

}