ios - 开始触摸的计数不等于完成触摸的计数

Question

我有以下代码用于测试目的:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self customTouchHandler:touches];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self customTouchHandler:touches];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self customTouchHandler:touches];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    [self customTouchHandler:touches];
}
- (void)customTouchHandler:(NSSet *)touches
{
    for(UITouch* touch in touches){
        if(touch.phase == UITouchPhaseBegan)
            touchesStarted++;
        if(touch.phase == UITouchPhaseEnded || touch.phase == UITouchPhaseCancelled)
            touchesFinished++;
    }
    NSLog(@"%d / %d", touchesStarted, touchesFinished);
}

我想当屏幕上没有触摸时，touchesStarted 应该总是等于 touchesFinished，但我有一个非常奇怪的输出:

2014-04-16 13:44:27.780 App[5925:60b] 2 / 0
2014-04-16 13:44:27.911 App[5925:60b] 2 / 1

我用两根手指按下屏幕，然后几乎(但不是)同时松开。

我错过了什么吗？为我的 View 启用了多点触控。对了， View 是SKView，代码属于我自定义的SKScene。

更新

由于你们中的许多人无法重现这种奇怪的行为，我准备了一个示例 Xcode 项目:https://www.dropbox.com/s/qmgxka1gtgwquio/TapTest.zip

尝试多次同时用两根手指敲击。当你移开手指时，touchesStarted 必须等于 touchesEnded，对吗？但他们不是。这是我的输出:

2014-04-24 12:49:06.359 TapTest[8207:60b] 1 / 0
2014-04-24 12:49:06.376 TapTest[8207:60b] 2 / 0
2014-04-24 12:49:06.458 TapTest[8207:60b] 2 / 0
2014-04-24 12:49:06.460 TapTest[8207:60b] 2 / 1
2014-04-24 12:49:06.491 TapTest[8207:60b] 2 / 2
2014-04-24 12:49:07.325 TapTest[8207:60b] 3 / 2
2014-04-24 12:49:07.342 TapTest[8207:60b] 4 / 2
2014-04-24 12:49:07.408 TapTest[8207:60b] 4 / 2
2014-04-24 12:49:07.410 TapTest[8207:60b] 4 / 3
2014-04-24 12:49:07.426 TapTest[8207:60b] 4 / 3
2014-04-24 12:49:07.441 TapTest[8207:60b] 4 / 4
2014-04-24 12:49:07.842 TapTest[8207:60b] 6 / 4
2014-04-24 12:49:07.925 TapTest[8207:60b] 6 / 4
2014-04-24 12:49:07.941 TapTest[8207:60b] 6 / 5
2014-04-24 12:49:08.042 TapTest[8207:60b] 8 / 5
2014-04-24 12:49:08.125 TapTest[8207:60b] 8 / 6
2014-04-24 12:49:08.259 TapTest[8207:60b] 9 / 6
2014-04-24 12:49:08.293 TapTest[8207:60b] 9 / 6
2014-04-24 12:49:08.308 TapTest[8207:60b] 9 / 7
2014-04-24 12:49:08.425 TapTest[8207:60b] 10 / 7
2014-04-24 12:49:08.442 TapTest[8207:60b] 11 / 7
2014-04-24 12:49:08.444 TapTest[8207:60b] 11 / 7
2014-04-24 12:49:08.492 TapTest[8207:60b] 11 / 8
2014-04-24 12:49:08.575 TapTest[8207:60b] 11 / 9
2014-04-24 12:49:08.642 TapTest[8207:60b] 12 / 9
2014-04-24 12:49:08.659 TapTest[8207:60b] 13 / 9
2014-04-24 12:49:08.660 TapTest[8207:60b] 13 / 9
2014-04-24 12:49:08.692 TapTest[8207:60b] 13 / 9
2014-04-24 12:49:08.694 TapTest[8207:60b] 13 / 10
2014-04-24 12:49:08.708 TapTest[8207:60b] 13 / 10
2014-04-24 12:49:08.741 TapTest[8207:60b] 13 / 11
2014-04-24 12:49:08.792 TapTest[8207:60b] 14 / 11
2014-04-24 12:49:08.809 TapTest[8207:60b] 15 / 11
2014-04-24 12:49:08.810 TapTest[8207:60b] 15 / 11
2014-04-24 12:49:08.890 TapTest[8207:60b] 15 / 11
2014-04-24 12:49:08.892 TapTest[8207:60b] 15 / 12
2014-04-24 12:49:08.908 TapTest[8207:60b] 15 / 13
2014-04-24 12:49:09.042 TapTest[8207:60b] 17 / 13
2014-04-24 12:49:09.141 TapTest[8207:60b] 17 / 14
2014-04-24 12:49:09.242 TapTest[8207:60b] 19 / 14
2014-04-24 12:49:09.341 TapTest[8207:60b] 19 / 14
2014-04-24 12:49:09.358 TapTest[8207:60b] 19 / 15
2014-04-24 12:49:09.441 TapTest[8207:60b] 21 / 15
2014-04-24 12:49:09.525 TapTest[8207:60b] 21 / 15
2014-04-24 12:49:09.542 TapTest[8207:60b] 21 / 15
2014-04-24 12:49:09.559 TapTest[8207:60b] 21 / 16
2014-04-24 12:49:09.608 TapTest[8207:60b] 22 / 16
2014-04-24 12:49:09.625 TapTest[8207:60b] 23 / 16
2014-04-24 12:49:09.626 TapTest[8207:60b] 23 / 16
2014-04-24 12:49:09.708 TapTest[8207:60b] 23 / 16
2014-04-24 12:49:09.709 TapTest[8207:60b] 23 / 17
2014-04-24 12:49:09.774 TapTest[8207:60b] 23 / 18
2014-04-24 12:49:09.810 TapTest[8207:60b] 24 / 18
2014-04-24 12:49:09.826 TapTest[8207:60b] 25 / 18
2014-04-24 12:49:09.828 TapTest[8207:60b] 25 / 18
2014-04-24 12:49:09.908 TapTest[8207:60b] 25 / 18
2014-04-24 12:49:09.909 TapTest[8207:60b] 25 / 19
2014-04-24 12:49:09.974 TapTest[8207:60b] 25 / 20
2014-04-24 12:49:09.992 TapTest[8207:60b] 26 / 20
2014-04-24 12:49:10.026 TapTest[8207:60b] 27 / 20
2014-04-24 12:49:10.027 TapTest[8207:60b] 27 / 20
2014-04-24 12:49:10.091 TapTest[8207:60b] 27 / 20
2014-04-24 12:49:10.094 TapTest[8207:60b] 27 / 21
2014-04-24 12:49:10.125 TapTest[8207:60b] 27 / 22

Answer 1

也有这个问题。

目前我根据观察触摸阶段找到的唯一解决方案:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    NSLog(@"Began %lu of %lu", [touches count], [event.allTouches count]);

    for (UITouch *touch in touches) {
        [touch addObserver:self forKeyPath:@"phase" options:0 context:nil];
    }
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    NSLog(@"Ended %lu of %lu", [touches count], [event.allTouches count]);
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

    if ([object isKindOfClass:[UITouch class]]) {
        UITouch *touch = object;
        NSLog(@"Touch %lu phase: %ld", (unsigned long)[touch hash], [touch phase]);
        if (touch.phase == UITouchPhaseEnded || touch.phase == UITouchPhaseCancelled) {
            NSLog(@"Touch %lu ended", (unsigned long)[touch hash]);
            [touch removeObserver:self forKeyPath:@"phase"];
        }
    }
}