ios - 秒表的启动和停止功能不协调 iOS

Question

我正在创建秒表，但启动和停止功能不协调。当计时器停止时，它不会从它离开的地方开始。

代码如下所示:

self.endDate = [NSDate dateWithTimeIntervalSinceNow:12.0f*60.0f];

-(void)startPressed:(id)sender{
    if(!_running){
        _running = TRUE;
        [sender setTitle:@"Stop" forState:UIControlStateNormal];
        if (_stopTimer == nil) {
            _stopTimer = [NSTimer scheduledTimerWithTimeInterval:1.0/10.0
                                                         target:self
                                                        selector:@selector(changeTimer:)
                                                       userInfo:nil
                                                        repeats:YES];
        }
    }else{
        _running = FALSE;
        [sender setTitle:@"Start" forState:UIControlStateNormal];
        [_stopTimer invalidate];
        _stopTimer = nil;
    }

}

- (void)changeTimer:(NSTimer*)timer {
    _timeInterval = [self.endDate timeIntervalSinceNow];
    self.timerControl1.minutesOrSeconds = ((NSInteger)_timeInterval)%60;
    self.timerControl2.minutesOrSeconds = (NSInteger)(_timeInterval/60.0f);
    self.timerControl3.minutesOrSeconds = ((NSInteger)_timeInterval)%60;
}

我知道这是因为 timeIntervalSinceNow。但是，如何改变这一点？在这方面需要一些指导。

问题:

例如，当您停止秒表并在 3 秒后再次启动时，它仍应从相同的时间重新开始。但是我的代码，开始和停止时间是不同的，它们是从不同的时间开始的。需要帮助来解决这个问题。

Answer 1

不要在 changeTimer 中使用 endDate，而是仅使用 endDate 来初始化计时器

#import "RimsViewController.h"

@interface RimsViewController ()
@property(weak) IBOutlet UILabel *label;
@property(strong) NSDate *endDate;
@end

@implementation RimsViewController {
    BOOL _running;
    NSTimeInterval _timeInterval;
    NSTimer *_stopTimer;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.endDate = [NSDate dateWithTimeIntervalSinceNow:10*60];
    _timeInterval = [self.endDate timeIntervalSinceNow];
}

-(IBAction)startPressed:(id)sender{
    if(!_running){
        _running = TRUE;
        [sender setTitle:@"Stop" forState:UIControlStateNormal];
        if (_stopTimer == nil) {
            _stopTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                                          target:self
                                                        selector:@selector(changeTimer:)
                                                        userInfo:nil
                                                         repeats:YES];
        }
    }else{
        _running = FALSE;
        [sender setTitle:@"Start" forState:UIControlStateNormal];
        [_stopTimer invalidate];
        _stopTimer = nil;
    }

}

- (void)changeTimer:(NSTimer*)timer {
    _timeInterval -= 1;// [self.endDate timeIntervalSinceNow];

    NSUInteger secs = _timeInterval;
    int h = (NSUInteger)secs/3600;
    secs-=h*3600;
    int m = (NSUInteger)secs/60;
    secs-=m*60;
    int s = secs;

    self.label.text = [NSString stringWithFormat:@"%d / %d / %d", h, m, s];
}

@end