UISwipeGestureRecognizer UIGestureRecognizerStateChanged未调用

Question

我在我的应用程序中定义了两个UISwipeGestureRecognizer：

UISwipeGestureRecognizer *swipeLeftVolume = [[UISwipeGestureRecognizer alloc]  initWithTarget:self action:@selector(handleSwipeGestureVolume:)];
swipeLeftVolume.direction = UISwipeGestureRecognizerDirectionLeft;
[self.playerView addGestureRecognizer:swipeLeftVolume];

UISwipeGestureRecognizer *swipeRightVolume = [[UISwipeGestureRecognizer alloc]  initWithTarget:self action:@selector(handleSwipeGestureVolume:)];
swipeRightVolume.direction = UISwipeGestureRecognizerDirectionRight;
[self.playerView addGestureRecognizer:swipeRightVolume];

在目标方法中，我有三个状态：

UIGestureRecognizerStateBegan
UIGestureRecognizerStateChanged
UIGestureRecognizerStateEnded

我注意到只有UIGestureRecognizerStateEnded才被调用。

知道有什么问题吗？我想识别特定UIView上的滑动：

- (void)handleSwipeGestureVolume:(UISwipeGestureRecognizer *)sender {
    if (sender.state == UIGestureRecognizerStateBegan) {
        NSLog(@"Start");
    } else if (sender.state == UIGestureRecognizerStateChanged) {
        NSLog(@"Changed");
    } else if (sender.state == UIGestureRecognizerStateEnded) {
        NSLog(@"Finish");
    }
}

Answer 1

确保为self.playerView.启用了UserInteraction

Answer 2

似乎您在UISwipeGestureRecognizer和UIPanGestureRecognizer之间感到困惑。

UISwipeGestureRecognizer只生成UIGestureRecognizerStateEnded状态，而UIPanGestureRecognizer具有所需的3种状态。

如果您需要同时接收UIGestureRecognizerStateBegan、UIGestureRecognizerStateChanged、UIGestureRecognizerStateEnded，请使用UIPanGestureRecognizer。

UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc]  initWithTarget:self action:@selector(handleSwipeGestureVolume:)];
[self.playerView addGestureRecognizer:panGesture];

Answer 3

对于任何手势识别器，必须启用用户交互才能工作。没有它，所有的手势都不会被触发，包括touchBegan:、touchMove:等。

所以你需要让[self.playerView setUserInteractionEnabled:TRUE];

还有一件事，我想让您知道，如果您已经实现了touchBegan:、touchMove:等，那么这个方法将首先被用于手势而不是UIGestureRecognizer shilds。