我想知道如何将长按手势识别器添加到 UICollectionView 的（子类）。我在文档中读到它是默认添加的，但我不知道如何。
我想做的是：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。我需要知道长按的是哪个单元格。抱歉这个广泛的问题，但我在谷歌或 SO 上找不到更好的东西
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9 回答
224
Objective-C
在您的myCollectionViewController.h文件中添加UIGestureRecognizerDelegate协议
@interface myCollectionViewController : UICollectionViewController<UIGestureRecognizerDelegate>
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
}
}
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))
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))
于 2013-09-17T11:36:05.593 回答
31
相同的代码@abbood 的 Swift 代码：
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)
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
}
}
不要忘记代表UIGestureRecognizerDelegate
于 2015-10-26T18:28:58.280 回答
14
斯威夫特 5：
private func setupLongGestureRecognizerOnCollection() {
let longPressedGesture = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress(gestureRecognizer:)))
longPressedGesture.minimumPressDuration = 0.5
longPressedGesture.delegate = self
longPressedGesture.delaysTouchesBegan = true
collectionView?.addGestureRecognizer(longPressedGesture)
}
@objc func handleLongPress(gestureRecognizer: UILongPressGestureRecognizer) {
if (gestureRecognizer.state != .began) {
return
}
let p = gestureRecognizer.location(in: collectionView)
if let indexPath = collectionView?.indexPathForItem(at: p) {
print("Long press at item: \(indexPath.row)")
}
}
也不要忘记实现 UIGestureRecognizerDelegate 并从 viewDidLoad 或任何您需要调用它的地方调用 setupLongGestureRecognizerOnCollection。
于 2020-06-06T14:46:26.857 回答
12
使用 UICollectionView 的委托接收长按事件
您必须实现以下 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
}
于 2016-04-28T11:20:21.223 回答
8
此处添加自定义长按手势识别器的答案是正确的，但是根据此处的文档：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。
以下代码将避免您的自定义手势识别器干扰默认手势识别器：
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];
}
于 2013-09-17T12:15:26.463 回答
2
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
[cell addGestureRecognizer:longPress];
并添加这样的方法。
- (void)longPress:(UILongPressGestureRecognizer*)gesture
{
if ( gesture.state == UIGestureRecognizerStateEnded ) {
UICollectionViewCell *cellLongPressed = (UICollectionViewCell *) gesture.view;
}
}
于 2013-09-17T11:38:08.360 回答
2
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：
添加您的手势识别器，设置它并在某处捕获它的引用（如果您将 UICollectionView 子类化，最好的选择是在您的子类上）
@interface UICollectionViewSubclass : UICollectionView <UIGestureRecognizerDelegate>
@property (strong, nonatomic, readonly) UILongPressGestureRecognizer *longPressGestureRecognizer;
@end
覆盖默认初始化方法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
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，设置与 UICollectionView 手势识别器的依赖关系（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）并向视图添加手势
-(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];
}
也不要忘记实现 UIGestureRecognizerDelegate 方法，使该手势失败并允许同时识别（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;
}
于 2015-12-28T15:56:55.097 回答
1
更简单的解决方案。
在您的cellForItemAt委托中（稍后设置 .tag 属性）：
cell.gestureRecognizers?.removeAll()
cell.tag = indexPath.row
let directFullPreviewer = UILongPressGestureRecognizer(target: self, action: #selector(directFullPreviewLongPressAction))
cell.addGestureRecognizer(directFullPreviewer)
并回调 longPress：
@objc func directFullPreviewLongPressAction(g: UILongPressGestureRecognizer)
{
if g.state == UIGestureRecognizer.State.began
{
// Get index as g.view.tag and that's it
}
}
于 2021-05-19T13:01:26.983 回答
0
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：
- 有时，当我们移动触摸时，这个识别器会以不正确的方式工作；
- 识别器拦截其他触摸动作，因此我们不能以正确的方式使用 UICollectionView 的高亮回调。
让我建议一个有点蛮力，但按照需要的建议工作：
为长按我们的单元格声明一个回调描述：
typealias OnLongClickListener = (view: OurCellView) -> Void
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
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)
}
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)
}
然后在我们集合视图的控制器中的某个地方声明回调监听器：
let longClickListener: OnLongClickListener = {view in
print("Long click was performed!")
}
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
}
现在我们可以拦截对单元格的长按操作。
于 2016-08-12T16:26:21.460 回答