Question

我正在设计一个我希望能够暂停并从同一个地方继续的计时器。我试过这样做，但代码对我不起作用。这是我的代码：

.m文件：

-(IBAction)buttonPause:(id)sender {
    NSString *dateString = timer.text;
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"HH:mm:ss.SS"];
    NSDate *dateFromString = [[NSDate alloc] init];
    dateFromString = [dateFormatter dateFromString:dateString];
    dateFromString = startDate;
}

- (IBAction)buttonStart:(id)sender {
    startDate = [NSDate date];
    stopWatchTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/100.0
                                                          target:self
                                                        selector:@selector(updateTimer)
                                                        userInfo:nil
                                                         repeats:YES];
}

- (void)updateTimer{
    NSDate *currentDate = [NSDate date];
    NSTimeInterval timeInterval = [currentDate timeIntervalSinceDate:startDate];
    NSDate *timerDate = [NSDate dateWithTimeIntervalSince1970:timeInterval];
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"HH:mm:ss.SS"];
    [dateFormatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0.0]];
    NSString *timeString = [dateFormatter stringFromDate:timerDate];
    timer.text = timeString;
}

我的问题似乎在于buttonPause方法。我做错了什么或不做什么？先谢谢你。

Answer 1

您可以使用NSTimeInterval而不是计时器。我有一个功能代码来暂停和停止计时器。

@interface PerformBenchmarksViewController () {

    int currMinute;
    int currSecond;
    int currHour;
    int mins;
    NSDate *startDate;
    NSTimeInterval secondsAlreadyRun;
}

@end

- (void)viewDidLoad
{
    [super viewDidLoad];

    running = false;
}

- (IBAction)StartTimer:(id)sender {

    if(running == false) {

        //start timer
        running = true;
        startDate = [[NSDate alloc] init];
        startTime = [NSDate timeIntervalSinceReferenceDate];
        [sender setTitle:@"Pause" forState:UIControlStateNormal];
        [self updateTime];
    }
    else {
        //pause timer
        secondsAlreadyRun += [[NSDate date] timeIntervalSinceDate:startDate];
        startDate = [[NSDate alloc] init];
        [sender setTitle:@"Start" forState:UIControlStateNormal];
        running = false;
    }
}

- (void)updateTime {

    if(running == false) return;

    //calculate elapsed time
    NSTimeInterval currentTime = [NSDate timeIntervalSinceReferenceDate];
    NSTimeInterval elapsed = secondsAlreadyRun + currentTime - startTime;

    // extract out the minutes, seconds, and hours of seconds from elapsed time:
    int hours = (int)(mins / 60.0);
    elapsed -= hours * 60;
    mins = (int)(elapsed / 60.0);
    elapsed -= mins * 60;
    int secs = (int) (elapsed);

    //update our lable using the format of 00:00:00
    timerLabel.text = [NSString stringWithFormat:@"%02u:%02u:%02u", hours, mins, secs];

    //call uptadeTime again after 1 second
    [self performSelector:@selector(updateTime) withObject:self afterDelay:1];
}

希望这会有所帮助。感谢

如何暂停秒表，然后从它开始的地方重新开始？

1 个答案: