xcode UISwipeGestureRecognizer 只有一个方向工作

UISwipeGestureRecognizer only one direction working

提问by ddolce

So Im making a page with pageControl (it's a page with multiple views with dots indicating which page you're in), my code looks like the following in viewDidLoad:

因此，我使用 pageControl 创建了一个页面（这是一个带有多个视图的页面，其中的点指示您所在的页面），我的代码如下所示viewDidLoad：

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];

And in the swipeAction selector I have:

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
    }
}

To my surprise, this method only works when you swipe to the right (i.e. the else ifblock gets called). When you swipe left, the swipeActiondoesn't even get called! This is strange, why does this happen and how should I change my code? Any reply is appreciated. Thanks a lot!

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

回答by Mick MacCallum

There's a couple things you should be aware of here. First, you have to create a gesture for each direction that you want to observe. This isn't a big deal though because you can simple give them the same selector, and it will be just like one gesture for two directions.

这里有几件事你应该注意。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];

Second, you never specified the direction of the gesture leaving it to default to right (or 1 on the direction enum)

其次，您从未指定手势的方向，使其默认为右（或方向枚举上的 1）

From the documentation:

从文档：

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

默认方向是 UISwipeGestureRecognizerDirectionRight。有关更多信息，请参阅 UISwipeGestureRecognizerDirection 常量的说明。

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

回答by Andrew Hodel

Swift 4

斯威夫特 4

let swiper = UISwipeGestureRecognizer(target: self, action: #selector(self.swipeFunction(sender:)))
swiper.direction = UISwipeGestureRecognizer.Direction.right
let swipel = UISwipeGestureRecognizer(target: self, action: #selector(self.swipeFunction(sender:)))
swipel.direction = UISwipeGestureRecognizer.Direction.left
UIView().addGestureRecognizer(swiper)
UIView().addGestureRecognizer(swipel)

@objc func swipeFunction(sender: UISwipeGestureRecognizer) {
    print(sender)
}

you should be able to figure it out from there, you add a UISwipeGestureRecognizer for each direction to the UIView

你应该能够从那里弄清楚，你为每个方向添加一个 UISwipeGestureRecognizer 到 UIView

回答by joeld

swipe.direction sets the direction(s) you're recognizing, it doesn't tell you which direction was swiped. Add this line when creating your recognizer:

swipe.direction 设置您识别的方向，它不会告诉您滑动的方向。创建识别器时添加此行：

swipe.direction = UISwipeGestureRecognizerDirectionLeft|UISwipeGestureRecognizerDirectionRight;

If you need to detect which direction was swiped, just use two different Recognizers, one for left and one for right.

如果您需要检测滑动的方向，只需使用两种不同的识别器，一种用于左侧，一种用于右侧。