Question

int maximumMinute;

NSTimer *timer;

- (void)startTimer: (int) minute {
maximumMinute = minute;
timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(countDown) userInfo:nil repeats:YES];

}

- (void)countDown {

maximumMinute -= 1;
self.timerLabel.text =  [NSString stringWithFormat:@"%i", maximumMinute];
if (maximumMinute == 0) {
    [timer invalidate];
}
}

这是我的计时器代码，我只是在viewDidLoad

中启动计时器

当单击某个视图进行测试时，我调用了此方法。

   -(void)clickSomthing: (UITapGestureRecognizer *)recognizer {
    int i = 0;
while ([timer isValid])
{
    NSLog(@"timer valid");
}

首先，当加载视图时，会触发计时器计数，我可以看到实际倒计时的次数，但是当我点击与方法相关的任何视图时，单击“#Something＆＃34;计时器不会倒计时实际停止。

我真正想做的是我希望计时器继续运行，直到它达到零，无论是何时或循环。实际上，我试图基于计时器停止我的游戏，但游戏确实需要一些while循环和循环需要一段时间。

Answer 1

你的代码锁定主线程（你永远不应该这样做）你应该使用GCD - Grand Central Dispatch在用户继续使用应用程序的同时在后台进行倒计时。

-(void)clickSomthing: (UITapGestureRecognizer *)recognizer {

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{

        int countDown = 10; // This is the countdown time
        BOOL letTheCountDown = TRUE;
        while (letTheCountDown) {
            [NSThread sleepForTimeInterval:1.0]; // Count second by second
            countDown--;
            NSLog(@"countDown %i",countDown);

            if (countDown == 0) {
                letTheCountDown = FALSE;                                    
                dispatch_async(dispatch_get_main_queue(), ^{
                    // Do something in main thread here. Ex: alert
                    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:@"Time is Over" delegate:self cancelButtonTitle:@"Okay" otherButtonTitles:nil];
                    [alert show];
                });
            }

        }

    });

}

NSTimer在while循环

1 个答案: