UITapGestureIdentiizer 点击 self. view 但忽略子视图

我需要实现一个特性，当我双击 self. view (UIViewController视图)时，它将调用一些代码。但问题是，我在这个视图上有其他 UI 对象，而且我不想将任何识别器对象附加到所有这些对象上。我发现这个方法下面如何使姿态对我的看法，我知道它是如何工作的。现在我面前的障碍，哪种方式选择创建这个识别忽略子视图。有什么想法吗？谢谢。

UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
[doubleTap setNumberOfTapsRequired:2];
[self.view addGestureRecognizer:doubleTap];
72639 次浏览
小开
最佳答案

You should adopt the UIGestureRecognizerDelegate protocol inside the self object and call the below method for checking the view. Inside this method, check your view against touch.view and return the appropriate bool (Yes/No). Something like this:

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
if ([touch.view isDescendantOfView:yourSubView]) {
return NO;
}
return YES;
}

Edit: Please, also check @Ian's answer!

Swift 5

// MARK: UIGestureRecognizerDelegate methods, You need to set the delegate of the recognizer
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
if touch.view?.isDescendant(of: tableView) == true {
return false
}
return true
}
小开

And for the Swift variant:

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldReceiveTouch touch: UITouch) -> Bool {
if touch.view.isDescendantOfView(yourSubView){
return false
}
return true
}

Good to know, isDescendantOfView returns a Boolean value indicating whether the receiver is a subview of a given view or identical to that view.

小开

Another approach is to just compare if the view of the touch is the gestures view, because descendants won't pass the condition. A nice, simple one-liner:

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
return touch.view == gestureRecognizer.view
}
小开

Complete swift solution (delegate must be implemented AND set for recognizer(s) ):

class MyViewController: UIViewController UIGestureRecognizerDelegate {


override func viewDidLoad() {
let doubleTapRecognizer = UITapGestureRecognizer(target: self, action: #selector(onBaseTapOnly))
doubleTapRecognizer.numberOfTapsRequired = 2
doubleTapRecognizer.delegate = self
self.view.addGestureRecognizer(doubleTapRecognizer)
}


func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldReceiveTouch touch: UITouch) -> Bool {
if touch.view.isDescendantOfView(self.view){
return false
}
return true
}


func onBaseTapOnly(sender: UITapGestureRecognizer) {
if sender.state == .Ended {
//react to tap
}
}
}
小开

Note that the gestureRecognizer API has changed to:

gestureRecognizer(_:shouldReceive:)

Take particular note of the underscore (skip) indicator for the first parameter's external label.

Using many of the examples provided above, I was not receiving the event. Below is a an example that works for current versions of Swift (3+). 

public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
var shouldReceive = false
if let clickedView = touch.view {
if clickedView == self.view {
shouldReceive = true;
}
}
return shouldReceive
}
小开

Plus the above solutions, do not forget to check User Interaction Enabled of your sub-view.

enter image description here

小开

Variant using CGPoint you touch (SWIFT 4.0)

class MyViewController: UIViewController, UIGestureRecognizerDelegate {


func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {


// Get the location in CGPoint
let location = touch.location(in: nil)


// Check if location is inside the view to avoid
if viewToAvoid.frame.contains(location) {
return false
}


return true
}
}
小开

With Swift 5 and iOS 12, UIGestureRecognizerDelegate has a method called gestureRecognizer(_:shouldReceive:). gestureRecognizer(_:shouldReceive:) has the following declaration:

Ask the delegate if a gesture recognizer should receive an object representing a touch.

optional func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool

The complete code below shows a possible implementation for gestureRecognizer(_:shouldReceive:). With this code, a tap on a subview of the ViewController's view (including imageView) won't trigger the printHello(_:) method.

import UIKit


class ViewController: UIViewController, UIGestureRecognizerDelegate {


override func viewDidLoad() {
super.viewDidLoad()


let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(printHello))
tapGestureRecognizer.delegate = self
view.addGestureRecognizer(tapGestureRecognizer)


let imageView = UIImageView(image: UIImage(named: "icon")!)
imageView.frame = CGRect(x: 50, y: 50, width: 100, height: 100)
view.addSubview(imageView)


// ⚠️ Enable user interaction for imageView so that it can participate to touch events.
// Otherwise, taps on imageView will be forwarded to its superview and managed by it.
imageView.isUserInteractionEnabled = true
}


func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
// Prevent subviews of a specific view to send touch events to the view's gesture recognizers.
if let touchedView = touch.view, let gestureView = gestureRecognizer.view, touchedView.isDescendant(of: gestureView), touchedView !== gestureView {
return false
}
return true
}


@objc func printHello(_ sender: UITapGestureRecognizer) {
print("Hello")
}


}

An alternative implementation of gestureRecognizer(_:shouldReceive:) can be:

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
return gestureRecognizer.view === touch.view
}

Note however that this alternative code does not check if touch.view is a subview of gestureRecognizer.view.

小开

Swift 4:

touch.view is now an optional, so based on @Antoine's answer:

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
if let touchedView = touch.view, touchedView.isDescendant(of: deductibleBackgroundView) {
return false
}
return true
}
小开

I had to prevent the gesture on the child view. The only thing that worked is to allow and keep the first view and prevent gesture in all the next views:

   var gestureView: UIView? = nil


func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
if (gestureView == nil || gestureView == touch.view){
gestureView = touch.view
return true
}
return false
}
小开

Clear Swift way

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
return touch.view == self.view
}
小开

If you don't want your 'double-tap recogniser' to conflict with your buttons and/or other controls, you can set self as UIGestureRecognizerDelegate and implement:

func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool
{
return !(touch.view is UIControl)
}
小开

Another solution may be found with the hitTest function, which

Returns the farthest descendant of the receiver in the view hierarchy (including itself) that contains a specified point.

By this way defining the UIGestureRecognizerDelegate is not necessary:

@objc func tapFunction (_ recognizer : UITapGestureRecognizer) {
if let viewTouched = recognizer.view?.hitTest(recognizer.location(in: recognizer.view), with: nil) {
if viewTouched == self.parentView {
//the parent view is tapped!
}
}
}

提交答案