ios - 为什么是hitTest :withEvent: called three times for each touch?

我有一个UIView的子类，在其中重写了hitTest:withEvent:，如下所示:

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
    NSLog(@"Event = %@", event);
    return self;
}

对于 View 中的每次触摸，我都会看到对hitTest:withEvent:的三个调用。这三个调用是在润饰前进行的。输出如下:

2011-07-01 09:20:58.553 AppName[930:207] Event = <UITouchesEvent: 0x6a08360> timestamp: 4297.16 touches: {(
)}
2011-07-01 09:20:58.553 AppName[930:207] Event = <UITouchesEvent: 0x6a08360> timestamp: 4297.16 touches: {(
)}
2011-07-01 09:20:58.554 AppName[930:207] Event = <UITouchesEvent: 0x6a08360> timestamp: 4304.54 touches: {(
)}

根据时间戳和地址，看起来好像正在使用单个UITouchesEvent对象，并且直到第三个调用才正确设置了它的时间戳。谁能解释为什么hitTest:withEvent:这样被调用3次？我不是在寻找解决方法。我只想了解发生了什么。

最佳答案

我遇到了同样的问题，并且能够使用此代码解决它。即使pointInside和hitTest被调用了3次，但被触摸的UIView的touchesBegan(或touchesEnded)仅被调用了一次。

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    if (event.type == UIEventTypeTouches)
        NSLog(@"%@", self);
}


- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    if ([self pointInside:point withEvent:event])
        return self;

    return [super hitTest:point withEvent:event];
}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
    if (CGRectContainsPoint([self bounds], point))
    {
        if (event.type == UIEventTypeTouches)
        {
            return YES;
        }
    }

    return NO;
}

关于ios - 为什么是hitTest :withEvent: called three times for each touch?，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/6550107/