我如何暂停和恢复我的 NSTimer

Question

我有一个已经可以工作的 NSTimer，但是希望在您单击按钮时暂停它。除了暂停之外，这个按钮将我重定向到我的另一个视图，然后当我回到主视图时，他必须从你离开的地方继续。我已经有了暂停按钮，我打算继续计数调用 viewWillAppear 上的方法

这是我的代码：

- (void)viewDidLoad {
    [super viewDidLoad];
    [self setUp];
}

- (void) setUp {
    _startDate = [NSDate date];
    _timer = [NSTimer scheduledTimerWithTimeInterval: 1.0/100.0 target: self selector: @selector(timerUpdating) userInfo: nil repeats: true];
}

-(void)timerUpdating {

    NSDate *currentDate = [NSDate date];
    NSTimeInterval timeInterval = [currentDate timeIntervalSinceDate:_startDate];
    NSDate *timerDate  = [NSDate dateWithTimeIntervalSince1970:timeInterval];
    NSDateFormatter *dateFormater = [[NSDateFormatter alloc]init];
    [dateFormater setDateFormat:@"mm:ss"];
    [dateFormater setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0.0]];
    NSString *timeString = [dateFormater stringFromDate:timerDate];
    self.timerLabel.text = timeString;
    self.pauseTimeInterval = &(timeInterval);
}

- (IBAction)timerActionPause:(id)sender {
}

Answer 1

- (void)startTimer {
    if(_timer != nil) { // To make sure 
        [self stopTimer];
    }
    _timer = [NSTimer scheduledTimerWithTimeInterval: 1.0/100.0 target: self selector: @selector(timerUpdating) userInfo: nil repeats: true];
}

- (void)stopTimer {
    [_timer invalidate];
    _timer = nil;
}

- (void)resetTimer {
    [self stopTimer];
    [self startTimer];
}