objective-c - 多点触控touchesBegan

Question

我在尝试让 touchesBegan 响应多点触控时遇到了一些问题。

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{

NSSet *allTouches = [event allTouches]; 
for (UITouch *touch in allTouches) 
{ 
CGPoint location = [touch locationInView:touch.view];
if(CGRectContainsPoint(snare.frame, location) && lastButton != snare) {
    //Swap Image
    snareImg.image = snareImgDown;
    [self performSelector:@selector(swapBack) withObject:nil afterDelay:0.1];
    //Play Sound
    NSString *path = [[NSBundle mainBundle] pathForResource:@"snare" 
                                                     ofType:@"wav"];
    SystemSoundID soundID;
    AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:path]
                                     , &soundID);
    AudioServicesPlaySystemSound (soundID); 
    //
    lastButton = snare;
}
else if(CGRectContainsPoint(hiHat.frame, location) && lastButton != hiHat) {
    //Play Sound
    NSString *path = [[NSBundle mainBundle] pathForResource:@"hi_hat" 
                                                     ofType:@"wav"];
    SystemSoundID soundID;
    AudioServicesCreateSystemSoundID((CFURLRef)[NSURL fileURLWithPath:path]
                                     , &soundID);
    AudioServicesPlaySystemSound (soundID); 
    //
    lastButton = hiHat;
}

我不知道如何设置它以响应多点触控，现在 touchesBegan 仅适用于按下 1 次。我知道有一些东西就像我假设一个 for(UITOuch *t in something) 我不记得它是如何工作的。

有人知道怎么做吗？

Answer 1

除非您设置multipleTouchEnabled = YES，否则默认情况下您只会获得一次触摸。 .那么您的代码应该会按预期工作。