ios - UISwipeGestureRecognizer 只有一个方向工作

Question

所以我用 pageControl 创建一个页面(这是一个有多个 View 的页面，用点表示你在哪个页面)，我的代码在 viewDidLoad 中看起来像下面这样:

UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeAction:)];
UIView *temp = [[UIView alloc]initWithFrame:self.view.frame];
temp.backgroundColor = [UIColor clearColor];
[temp addGestureRecognizer:swipe];
[self.view addSubview:temp];

在 swipeAction 选择器中我有:

- (void)swipeAction: (UISwipeGestureRecognizer *)sender{
    NSLog(@"Swipe action called");
    if (sender.direction == UISwipeGestureRecognizerDirectionLeft) {
        //Do Something
    }
    else if (sender.direction == UISwipeGestureRecognizerDirectionRight){
        //Do Something Else
    }
}

令我惊讶的是，此方法仅在您向右滑动时有效(即调用 else if block )。当您向左滑动时，swipeAction 甚至都不会被调用!这很奇怪，为什么会发生这种情况，我应该如何更改我的代码？任何答复表示赞赏。非常感谢!

Answer 1

这里有几件事您应该注意。首先，您必须为要观察的每个方向创建一个手势。不过这没什么大不了的，因为您可以简单地为它们提供相同的选择器，这就像一个手势用于两个方向。

UISwipeGestureRecognizer *leftSwipe = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeAction:)];
leftSwipe.direction = UISwipeGestureRecognizerDirectionLeft;

UISwipeGestureRecognizer *rightSwipe = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeAction:)];
rightSwipe.direction = UISwipeGestureRecognizerDirectionRight;


UIView *temp = [[UIView alloc]initWithFrame:self.view.frame];

temp.backgroundColor = [UIColor clearColor];
[temp addGestureRecognizer:leftSwipe];
[temp addGestureRecognizer:rightSwipe];

[self.view addSubview:temp];

其次，您从未指定手势的方向，使其默认为右(或方向枚举中的 1)

来自documentation :

The default direction is UISwipeGestureRecognizerDirectionRight. See descriptions of UISwipeGestureRecognizerDirection constants for more information.

typedef enum {
   UISwipeGestureRecognizerDirectionRight = 1 << 0,
   UISwipeGestureRecognizerDirectionLeft  = 1 << 1,
   UISwipeGestureRecognizerDirectionUp    = 1 << 2,
   UISwipeGestureRecognizerDirectionDown  = 1 << 3
} UISwipeGestureRecognizerDirection;