ios UICollectionViewCell 上的长按手势

Long press gesture on UICollectionViewCell

提问by Oscar Apeland

I was wondering how to add a long press gesture recognizer to a (subclass of) UICollectionView. I read in the documentation that it is added by default, but I can't figure out how.

我想知道如何向 UICollectionView（的子类）添加长按手势识别器。我在文档中读到它是默认添加的，但我不知道如何添加。

What I want to do is: Long press on a cell ( I have a calendar thingy from github), get which cell is tapped and then do stuff with it. I need to know what cell is longpressed. Sorry for this broad question, but i couldn't find anything better on either google or SO

我想要做的是：长按一个单元格（我有一个来自 github 的日历），获取哪个单元格被点击，然后用它做一些事情。我需要知道长按什么单元格。很抱歉这个宽泛的问题，但我在 google 或 SO 上都找不到更好的东西

回答by abbood

Objective-C

目标-C

In your myCollectionViewController.hfile add the UIGestureRecognizerDelegateprotocol

在您的myCollectionViewController.h文件中添加UIGestureRecognizerDelegate协议

@interface myCollectionViewController : UICollectionViewController<UIGestureRecognizerDelegate>

in your myCollectionViewController.mfile:

在您的myCollectionViewController.m文件中：

- (void)viewDidLoad
{
    // attach long press gesture to collectionView
    UILongPressGestureRecognizer *lpgr 
       = [[UILongPressGestureRecognizer alloc]
                     initWithTarget:self action:@selector(handleLongPress:)];
    lpgr.delegate = self;
    lpgr.delaysTouchesBegan = YES;
    [self.collectionView addGestureRecognizer:lpgr];
}

-(void)handleLongPress:(UILongPressGestureRecognizer *)gestureRecognizer
{
    if (gestureRecognizer.state != UIGestureRecognizerStateEnded) {
        return;
    }
    CGPoint p = [gestureRecognizer locationInView:self.collectionView];

    NSIndexPath *indexPath = [self.collectionView indexPathForItemAtPoint:p];
    if (indexPath == nil){
        NSLog(@"couldn't find index path");            
    } else {
        // get the cell at indexPath (the one you long pressed)
        UICollectionViewCell* cell =
        [self.collectionView cellForItemAtIndexPath:indexPath];
        // do stuff with the cell
    }
}

Swift

迅速

class Some {

    @objc func handleLongPress(gesture : UILongPressGestureRecognizer!) {
        if gesture.state != .Ended {
            return
        }
        let p = gesture.locationInView(self.collectionView)

        if let indexPath = self.collectionView.indexPathForItemAtPoint(p) {
            // get the cell at indexPath (the one you long pressed)
            let cell = self.collectionView.cellForItemAtIndexPath(indexPath)
            // do stuff with the cell
        } else {
            print("couldn't find index path")
        }
    }
}

let some = Some()
let lpgr = UILongPressGestureRecognizer(target: some, action: #selector(Some.handleLongPress))

Swift 4

斯威夫特 4

class Some {

    @objc func handleLongPress(gesture : UILongPressGestureRecognizer!) {
        if gesture.state != .ended { 
            return 
        } 

        let p = gesture.location(in: self.collectionView) 

        if let indexPath = self.collectionView.indexPathForItem(at: p) { 
            // get the cell at indexPath (the one you long pressed) 
            let cell = self.collectionView.cellForItem(at: indexPath) 
            // do stuff with the cell 
        } else { 
            print("couldn't find index path") 
        }
    }
}

let some = Some()
let lpgr = UILongPressGestureRecognizer(target: some, action: #selector(Some.handleLongPress))

回答by Guilherme de Freitas

The same code @abbood's code for Swift:

与@abbood 的 Swift 代码相同的代码：

In viewDidLoad:

在 viewDidLoad 中：

let lpgr : UILongPressGestureRecognizer = UILongPressGestureRecognizer(target: self, action: "handleLongPress:")
lpgr.minimumPressDuration = 0.5
lpgr.delegate = self
lpgr.delaysTouchesBegan = true
self.collectionView?.addGestureRecognizer(lpgr)

And the function:

和功能：

func handleLongPress(gestureRecognizer : UILongPressGestureRecognizer){

    if (gestureRecognizer.state != UIGestureRecognizerState.Ended){
        return
    }

    let p = gestureRecognizer.locationInView(self.collectionView)

    if let indexPath : NSIndexPath = (self.collectionView?.indexPathForItemAtPoint(p))!{
        //do whatever you need to do
    }

}

Do not forget the delegate UIGestureRecognizerDelegate

不要忘记代表 UIGestureRecognizerDelegate

回答by liuyuning

Use the delegate of UICollectionView receive long press event

使用 UICollectionView 的委托接收长按事件

You must impl 3 method below.

您必须在下面实现 3 种方法。

//UICollectionView menu delegate
- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath{

   //Do something

   return YES;
}
- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender{
    //do nothing
    return NO;
}

- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender{
    //do nothing
}

回答by tiguero

Answers here to add a custom longpress gesture recognizer are correct howeveraccording to the documentation here: the parent class of UICollectionViewclass installs a default long-press gesture recognizerto handle scrolling interactions so you must link your custom tap gesture recognizer to the default recognizer associated with your collection view.

此处添加自定义长按手势识别器的答案是正确的，但根据此处的文档：类的父类UICollectionView安装 adefault long-press gesture recognizer来处理滚动交互，因此您必须将自定义点击手势识别器链接到与您的集合视图关联的默认识别器。

The following code will avoid your custom gesture recognizer to interfere with the default one:

以下代码将避免您的自定义手势识别器干扰默认识别器：

UILongPressGestureRecognizer* longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPressGesture:)];

longPressGesture.minimumPressDuration = .5; //seconds
longPressGesture.delegate = self;

// Make the default gesture recognizer wait until the custom one fails.
for (UIGestureRecognizer* aRecognizer in [self.collectionView gestureRecognizers]) {
   if ([aRecognizer isKindOfClass:[UILongPressGestureRecognizer class]])
      [aRecognizer requireGestureRecognizerToFail:longPressGesture];
} 

回答by Satheeshwaran

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];

[cell addGestureRecognizer:longPress];

and add the method like this.

并添加这样的方法。

- (void)longPress:(UILongPressGestureRecognizer*)gesture
{
    if ( gesture.state == UIGestureRecognizerStateEnded ) {

        UICollectionViewCell *cellLongPressed = (UICollectionViewCell *) gesture.view;
    }
}

回答by Dmitry Fantastik

To have an external gesture recognizer and do not conflict with internal gesture recognizers on the UICollectionView you need to:

要拥有外部手势识别器并且不与 UICollectionView 上的内部手势识别器冲突，您需要：

Add your gesture recognizer, set up it and capture a reference for it somewhere (the best option is on your subclass if you subclassed UICollectionView)

添加你的手势识别器，设置它并在某处捕获它的引用（如果你子类化 UICollectionView，最好的选择是在你的子类上）

@interface UICollectionViewSubclass : UICollectionView <UIGestureRecognizerDelegate>    

@property (strong, nonatomic, readonly) UILongPressGestureRecognizer *longPressGestureRecognizer;   

@end

Override default initialization methods initWithFrame:collectionViewLayout:and initWithCoder:and add set up method for you long press gesture recognizer

覆盖默认的初始化方法initWithFrame:collectionViewLayout:并initWithCoder:为您的长按手势识别器添加设置方法

@implementation UICollectionViewSubclass

-(instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout
{
    if (self = [super initWithFrame:frame collectionViewLayout:layout]) {
        [self setupLongPressGestureRecognizer];
    }
    return self;
}

-(instancetype)initWithCoder:(NSCoder *)aDecoder
{
    if (self = [super initWithCoder:aDecoder]) {
        [self setupLongPressGestureRecognizer];
    }
    return self;
}

@end

Write your setup method so it instantiates long press gesture recognizer, set it's delegate, setup dependencies with UICollectionView gesture recognizer (so it be the main gesture and all other gestures will wait till that gesture fails before being recognized) and add gesture to the view

编写您的设置方法，以便它实例化长按手势识别器，设置它的委托，使用 UICollectionView 手势识别器设置依赖项（因此它是主要手势，所有其他手势将等到该手势失败后再被识别）并将手势添加到视图

-(void)setupLongPressGestureRecognizer
{
    _longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self
                                                                                action:@selector(handleLongPressGesture:)];
    _longPressGestureRecognizer.delegate = self;

    for (UIGestureRecognizer *gestureRecognizer in self.collectionView.gestureRecognizers) {
        if ([gestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]]) {
            [gestureRecognizer requireGestureRecognizerToFail:_longPressGestureRecognizer];
        }
    }

    [self.collectionView addGestureRecognizer:_longPressGestureRecognizer];
}

Also don't forget to implement UIGestureRecognizerDelegate methods that fails that gesture and allow simultaneous recognition (you may or may don't need to implement it, it depends on other gesture recognizers you have or dependencies with internal gesture recognizers)

另外不要忘记实现使该手势失败并允许同时识别的 UIGestureRecognizerDelegate 方法（您可能需要也可能不需要实现它，这取决于您拥有的其他手势识别器或与内部手势识别器的依赖关系）

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    if ([self.longPressGestureRecognizer isEqual:gestureRecognizer]) {
        return NO;
    }

    return NO;
}

credentials for that goes to internal implementation of LXReorderableCollectionViewFlowLayout

用于LXReorderableCollectionViewFlowLayout 的内部实现的凭据

回答by Andrei K.

Perhaps, using UILongPressGestureRecognizeris the most widespread solution. But I encounter with it two annoying troubles:

也许，使用UILongPressGestureRecognizer是最普遍的解决方案。但是我遇到了两个烦人的麻烦：

• sometimes this recognizer works in incorrect way when we're moving our touch;
• recognizer intercepts other touch actions so we can't use highlight callbacks of our UICollectionView in a proper way.

• 有时，当我们移动触摸时，此识别器的工作方式不正确；
• 识别器会拦截其他触摸操作，因此我们无法以正确的方式使用 UICollectionView 的高亮回调。

Let me suggest one a little bit bruteforce, but working as it's required suggestion:

让我建议一点点蛮力，但按要求工作：

Declaring a callback description for long click on our cell:

声明长按单元格的回调描述：

typealias OnLongClickListener = (view: OurCellView) -> Void

typealias OnLongClickListener = (view: OurCellView) -> Void

Extending UICollectionViewCellwith variables (we can name it OurCellView, for example):

使用变量扩展UICollectionViewCell（例如，我们可以将其命名为 OurCellView）：

/// To catch long click events.
private var longClickListener: OnLongClickListener?

/// To check if we are holding button pressed long enough.
var longClickTimer: NSTimer?

/// Time duration to trigger long click listener.
private let longClickTriggerDuration = 0.5

Adding two methods in our cell class:

在我们的单元类中添加两个方法：

/**
 Sets optional callback to notify about long click.

 - Parameter listener: A callback itself.
 */
func setOnLongClickListener(listener: OnLongClickListener) {
    self.longClickListener = listener
}

/**
 Getting here when long click timer finishs normally.
 */
@objc func longClickPerformed() {
    self.longClickListener?(view: self)
}

And overriding touch events here:

并在此处覆盖触摸事件：

/// Intercepts touch began action.
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    longClickTimer = NSTimer.scheduledTimerWithTimeInterval(self.longClickTriggerDuration, target: self, selector: #selector(longClickPerformed), userInfo: nil, repeats: false)
    super.touchesBegan(touches, withEvent: event)
}

/// Intercepts touch ended action.
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
    longClickTimer?.invalidate()
    super.touchesEnded(touches, withEvent: event)
}

/// Intercepts touch moved action.
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
    longClickTimer?.invalidate()
    super.touchesMoved(touches, withEvent: event)
}

/// Intercepts touch cancelled action.
override func touchesCancelled(touches: Set<UITouch>?, withEvent event: UIEvent?) {
    longClickTimer?.invalidate()
    super.touchesCancelled(touches, withEvent: event)
}

Then somewhere in controller of our collection view declaring callback listener:

然后在我们的集合视图的控制器中的某个地方声明回调侦听器：

let longClickListener: OnLongClickListener = {view in
    print("Long click was performed!")
}

And finally in cellForItemAtIndexPathsetting callback for our cells:

最后在cellForItemAtIndexPath中为我们的单元格设置回调：

/// Data population.
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("Cell", forIndexPath: indexPath)
    let castedCell = cell as? OurCellView
    castedCell?.setOnLongClickListener(longClickListener)

    return cell
}

Now we can intercept long click actions on our cells.

现在我们可以拦截我们单元格上的长按操作。