xcode 如何使用 Interface Builder 设置 UIScreenEdgePanGestureRecognizer？

How do I set up an UIScreenEdgePanGestureRecognizer using Interface Builder?

提问by j b

I can't get UIScreenEdgePanGestureRecognizerto work when I create when I add it to my view controller using Interface Builder, so I'm asking here to establish whether I'm doing something wrong or if there is a bug in Xcode.

UIScreenEdgePanGestureRecognizer当我使用 Interface Builder 将它添加到我的视图控制器时，我无法开始工作，所以我在这里要求确定我是否做错了什么，或者 Xcode 中是否存在错误。

Here are the steps to reproduce:

以下是重现的步骤：

• Create a new Xcode project using the "Single View Application" template for iOS.
• Add a UIViewto the main view controller by dragging one from the Object Library in Interface Builder
• Add a UIScreenEdgePanGestureRecognizerto the view by dragging one from the Object Library in Interface Builder
• Ensure that the gesture recogniser is enabled and that an edge is selected:

• 使用适用于 iOS 的“单一视图应用程序”模板创建一个新的 Xcode 项目。
• UIView通过从 Interface Builder 中的对象库中拖动一个来将一个添加到主视图控制器
• UIScreenEdgePanGestureRecognizer通过从 Interface Builder 中的对象库中拖动一个来将一个添加到视图中
• 确保启用了手势识别器并选择了一条边：

• Open the assistant editor for the ViewControllerclass and ctrl-drag from the UIScreenEdgePanGestureRecognizerto the ViewController's implementation block to create a new IBAction` Add a breakpoint in the action's method body to test if the edge pan gesture is being recognized

• 打开类的辅助编辑器，ViewController按住ctrl键拖拽UIScreenEdgePanGestureRecognizer到ViewController实现块新建一个IBAction`在action方法体中添加断点，测试是否可以识别边缘平移手势

The resulting code is as follows:

结果代码如下：

If I run the application on my device (iPhone 6 running iOS 8.02) the breakpoint does not get hit when I do an edge swipe.

如果我在我的设备（运行 iOS 8.02 的 iPhone 6）上运行该应用程序，当我执行边缘滑动时，断点不会被击中。

Is there something I'm missing?

有什么我想念的吗？

UPDATE: this was filed as a bug with Apple (rdar://18582306) on 08-Oct-2014 and still isn't resolved in Xcode 6.4 (6E35b)

更新：这是在 2014 年 10 月 8 日作为 Apple (rdar://18582306) 的错误提交的，但在 Xcode 6.4 (6E35b) 中仍未解决

回答by sunergeos

I set up a project to test your question and found the same issue you did. Here are the scenarios I set up to test:

我建立了一个项目来测试您的问题，并发现了您所做的相同问题。以下是我为测试而设置的场景：

• I did exactly as you did, using Interface Builder, to build the screen edge gesture. The only difference in my code is that I put a line of code in the selector so the debugger would have something to stop on. The debugger failed to halt exactly as you found.

  -(void)handlePan:(id)sender
  {
      NSString *test = @"";
  }
  

• I then created an additional gesture using the pinch gesture on the same view using Interface Builder and I was able to get the debugger to halt within that selector. So Interface Builder seems to be able to build other gestures correctly.

• I then created the screen edge gesture manually using the following code and it worked as expected.

• 我和你做的完全一样，使用界面生成器来构建屏幕边缘手势。我的代码的唯一区别是我在选择器中放置了一行代码，以便调试器可以停止。调试器未能完全按照您的发现停止。

  -(void)handlePan:(id)sender
  {
      NSString *test = @"";
  }
  

• 然后，我使用 Interface Builder 在同一视图上使用捏合手势创建了一个额外的手势，并且我能够让调试器在该选择器内停止。因此 Interface Builder 似乎能够正确构建其他手势。

• 然后我使用以下代码手动创建了屏幕边缘手势，它按预期工作。

In the ViewController.h file I included the UIGestureRecognizerDelegate.

在 ViewController.h 文件中，我包含了 UIGestureRecognizerDelegate。

@interface ViewController : UIViewController <UIGestureRecognizerDelegate>
@end

In the ViewController.m file I implemented the gesture manually.

在 ViewController.m 文件中，我手动实现了手势。

#import "ViewController.h"

@interface ViewController ()

-(void)handlePan:(id)sender;

@end

@implementation ViewController

- (void)viewDidLoad 
{
    [super viewDidLoad];
    UIScreenEdgePanGestureRecognizer *pan = [[UIScreenEdgePanGestureRecognizer alloc] initWithTarget:self
                                                                                              action:@selector(handlePan:)];
    [pan setEdges:UIRectEdgeLeft];
    [pan setDelegate:self];
    [self.view addGestureRecognizer:pan];
}

-(void)handlePan:(id)sender
{
    NSString *test = @"";
}

@end

I ended up with the same conclusion you did - there seems to be something wrong with the Interface Builder's implementation of the UIScreenEdgePanGestureRecognizer.

我最终得到了与您相同的结论 - 界面生成器对 UIScreenEdgePanGestureRecognizer 的实现似乎有问题。

回答by Peter

I have tried it in Xcode 7.0 Beta 4 (7A165t) and it's still a bug. Adding the Screen Edge Pan Gesture Recognizer via Interface Builder doesn't call the referenced IBAction, however adding it programmatically like this works fine:

我已经在 Xcode 7.0 Beta 4 (7A165t) 中尝试过它，但它仍然是一个错误。通过 Interface Builder 添加 Screen Edge Pan Gesture Recognizer 不会调用引用的 IBAction，但是像这样以编程方式添加它可以正常工作：

class ViewController: UIViewController, UIGestureRecognizerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        let edgeGestureRecognizer = UIScreenEdgePanGestureRecognizer(target: self, action: "userSwipedFromEdge:")
        edgeGestureRecognizer.edges = UIRectEdge.Left
        edgeGestureRecognizer.delegate = self
        self.view.addGestureRecognizer(edgeGestureRecognizer)
    }

    func userSwipedFromEdge(sender: UIScreenEdgePanGestureRecognizer) {
        if sender.edges == UIRectEdge.Left {
            print("It works!")
        }
    }
}

Hint:Don't forget to add the UIGestureRecognizerDelegateprotocol to your class. Otherwise you'll get an error at edgeGestureRecognizer.delegate = self

提示：不要忘记将UIGestureRecognizerDelegate协议添加到您的类中。否则你会得到一个错误edgeGestureRecognizer.delegate = self

回答by Thomas LIU

It can be considered as a bug, but actually, here is something useful:

它可以被视为一个错误，但实际上，这里有一些有用的东西：

"After creating a screen edge pan gesture recognizer, assign an appropriate value to the edges property before attaching the gesture recognizer to your view."

“创建屏幕边缘平移手势识别器后，在将手势识别器附加到您的视图之前，为边缘属性分配适当的值。”

https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIScreenEdgePanGestureRecognizer_class/index.html

https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIScreenEdgePanGestureRecognizer_class/index.html

This requirement only apply to UIScreenEdgePanGestureRecognizer, so I think that's why Xcode make it wrong, it must be implemented as the normal sequence, alloc->init->attach->set value. It will work to all other GestureRecongnizer but not UIScreenEdgePanGestureRecognizer.

这个要求只适用于UIScreenEdgePanGestureRecognizer，所以我认为这就是Xcode出错的原因，它必须按照正常顺序来实现，alloc->init->attach->set value。它适用于所有其他 GestureRecongnizer，但不适用于 UIScreenEdgePanGestureRecognizer。

回答by Zelko

Xcode isn't always a good neighbor. Sorry.

Xcode 并不总是一个好邻居。对不起。

override func viewDidLoad() {
    super.viewDidLoad()

    let panGesture = UIScreenEdgePanGestureRecognizer(target: self, action: "panAction:")
    panGesture.edges = .Left
    view.addGestureRecognizer(panGesture)
}


func panAction(sender: UIScreenEdgePanGestureRecognizer) {
    let translation = sender.translationInView(sender.view!)

    println("Trans:\(translation)")
}

回答by zisoft

To make sure that multiple gesture recognizers can work together you have to implement the method shouldRecognizeSimultaneouslyWithGestureRecognizerand return true:

要确保多个手势识别器可以一起工作，您必须实现该方法shouldRecognizeSimultaneouslyWithGestureRecognizer并返回 true：

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

Sorry for the Swift code but you should get the idea.

对不起 Swift 代码，但你应该明白这个想法。

This method must be implemented even if you are using a single gesture recognizer because the view can have its own (system) recognizers, such as MKMapView.

即使您使用单个手势识别器，也必须实现此方法，因为视图可以拥有自己的（系统）识别器，例如MKMapView.

回答by drtofu

It seems that there is a bug in Xcode 6.4's interface builder and Swift. Also, Thomas LIU's answer was also correct: it seems to be necessary to set the .edge property in code, rather than with Interface Builder.

Xcode 6.4 的界面构建器和Swift 中似乎存在一个错误。此外，Thomas LIU 的回答也是正确的：似乎有必要在代码中设置 .edge 属性，而不是使用 Interface Builder。

Even though there are edge checkboxes in IB, they seem to be ignored.

即使 IB 中有边缘复选框，它们似乎也被忽略了。

I solved it this way: Ctrl-drag from the gesture recognizer to the viewController class to create an IBOutlet:

我是这样解决的：按住 Ctrl 键从手势识别器拖动到 viewController 类以创建一个 IBOutlet：

class ViewController: UIViewController {
    @IBOutlet var leftEdgeGestureRecognizer: UIScreenEdgePanGestureRecognizer!

then, in viewDidLoad:

然后，在 viewDidLoad 中：

leftEdgeGestureRecognizer.edges = .Left

and finally, ctrl-drag from the recognizer to create an IBAction

最后，从识别器按住 ctrl-drag 来创建一个 IBAction

@IBAction func swipeFromLeft(sender: AnyObject) {
        print("===> Swipe from left edge.\n")
}

回答by itsji10dra

Facing same issue from long. Its a xcode bug, its better to add it programmatically.

长期面临同样的问题。它是一个 xcode 错误，最好以编程方式添加它。