NSTimer如何解决我的代码

Question

如何编写代码如果timer1Elapsed完成倒数计时器然后转到下一个timer2Elapsed，倒计时后返回timer1Elapsed倒计时等等重复过程5次。似乎（A→B→A→B ... 5次）在条件A和B有固定时间，就说A计1分钟，B计30秒。请帮助，请不要错别字，因为我是初学者。纠正我，如果我的代码是错误的。请慷慨。

- (void) timer2Elapsed:(id)timer 
{ 
    ... 

    if (remainingTime <= 0) 
    { 
     [timer invalidate]; 
     [NSTimer scheduledTimerWithTimeInterval:0.99 target:self selector:@selector(timer3Elapsed:) userInfo:nil repeats:YES]; 
    } 

    myDisplay.text = [NSString stringWithFormat:@"%d : %d : %d", hour , minute, second]; 
} 

- (void) timer1Elapsed:(id)timer 
{ 
    ... 

    if (remainingTime <= 0) 
    { 
     [timer invalidate]; 
     [NSTimer scheduledTimerWithTimeInterval:0.99 target:self selector:@selector(timer2Elapsed:) userInfo:nil repeats:YES]; 
    } 

    myDisplay.text = [NSString stringWithFormat:@"%d : %d : %d", hour , minute, second]; 
} 

这是我的按钮

- (IBAction)startBtn:(id)sender { 
     [NSTimer scheduledTimerWithTimeInterval:0.99 target:self selector:@selector(timer1Elapsed:) userInfo:nil repeats:YES]; 
} 

Answer 1

如果你需要一个计时器来调用其他的，你可以使用下面的代码

+ (void) timer2Elapsed:(id)timer 
{ 
    static int numberOfTimes = 0; 
    if(numberOfTimes >= 5) 
    { 
     numberOfTimes = 0; 
     return; 
    } 
    numberOfTimes ++; 

    [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(timer1Elapsed:) userInfo:nil repeats:NO]; 
} 

- (void) timer1Elapsed:(id)timer 
{ 
    [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(timer2Elapsed:) userInfo:nil repeats:NO]; 
} 

- (void)startTimers 
{ 
    [NSTimer scheduledTimerWithTimeInterval:2 target:self selector:@selector(timer1Elapsed:) userInfo:nil repeats:NO]; 
}