UISwipeGestureRecognizer 在不应该执行的 if/else 语句中执行

Question

当用户滑动屏幕的左半部分时，我正在尝试在 iOS 7 Sprite Kit 中运行一个动作。

为了实现这一点，我创建了一个等待触摸事件的 for 循环，并且在触摸时，有一个 if 语句检查触摸位置是否小于视图边界的一半。 if 语句本身正在正确执行（如果在屏幕的右半部分启动触摸，则 else 半部分返回正确的 NSLog）。然而，由 UISwipeGestureRecognizer 触发的操作会被调用，而不管触摸是从哪里开始的。我在下面包含了一个代码示例。

这没有按预期工作是有原因的吗？

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
for (UITouch *touch in touches) {
    CGPoint touchLocation = [touch locationInView:self.view];
    NSLog(@"Touch location: %f, %f",touchLocation.x,touchLocation.y);

    if (touchLocation.x<self.view.bounds.size.width/2) {
        UISwipeGestureRecognizer *swipeRight = [[UISwipeGestureRecognizer alloc] initWithTarget:(self) action:@selector(screenSwipedRight)];
        swipeRight.numberOfTouchesRequired = 1;
        swipeRight.direction=UISwipeGestureRecognizerDirectionRight;
        [self.view addGestureRecognizer:(swipeRight)];

        UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:(self) action:@selector(screenSwipedLeft)];
        swipeLeft.numberOfTouchesRequired = 1;
        swipeLeft.direction=UISwipeGestureRecognizerDirectionLeft;
        [self.view addGestureRecognizer:(swipeLeft)];

        UISwipeGestureRecognizer *swipeUp = [[UISwipeGestureRecognizer alloc] initWithTarget:(self) action:@selector(screenSwipedUp)];
        swipeUp.numberOfTouchesRequired = 1;
        swipeUp.direction=UISwipeGestureRecognizerDirectionUp;
        [self.view addGestureRecognizer:(swipeUp)];
    }
    else {
        NSLog(@"Touches were on the right!");
    }
}
}


-(void)screenSwipedRight
{
    CGFloat percentToRight = 1-(self.playerOne.position.x / self.view.bounds.size.width);
    NSTimeInterval timeToRight = self.horizontalRunSpeed * percentToRight;
    NSLog(@"Percent to right = %f",percentToRight);
    NSLog(@"Time to right = %f",timeToRight);
    SKAction *moveNodeRight = [SKAction moveToX:self.view.bounds.size.width-self.playerOne.size.width duration:timeToRight];
    [self.playerOne runAction:[SKAction sequence:@[moveNodeRight]]];
}

Answer 1

这没有按预期工作是有原因的吗？

是的。每当屏幕左半部分开始有任何触摸时，您都将添加一组新的滑动手势识别器。你永远不会删除它们。您永远不会限制手势识别器开始的条件。

这应该可以解决您的问题：

1. 删除touchesBegan:withEvent: 的实现。
2. 在viewDidLoad 中添加您的手势识别器。
3. 为所有手势识别器设置delegate = self。

4. 添加此代码：

   - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
       CGPoint touchLocation = [touch locationInView:self.view];
       NSLog(@"Touch location: %f, %f",touchLocation.x,touchLocation.y);
       BOOL shouldBegin = (touchLocation.x < self.view.bounds.size.width / 2);
       return shouldBegin;
   }