如何在 UIImageView 上实现点击并按住？

Posted 2023-02-27

【中文标题】如何在 UIImageView 上实现点击并按住？

【英文标题】：How to implement a tap and hold on an UIImageView?

【发布时间】：2014-07-15 13:29:30

【问题描述】：

当我触摸并按住图像 2 秒钟时，我试图调用一个警告框。这是我到目前为止得到的：

- (void)viewDidLoad

    [super viewDidLoad];

    UILongPressGestureRecognizer *tapAndHoldGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapAndHoldGesture:)];
    tapAndHoldGesture.minimumPressDuration = 0.1;
    tapAndHoldGesture.allowableMovement = 600;
    [self.view addGestureRecognizer:tapAndHoldGesture]; 


- (void) handleTapAndHoldGesture:(UILongPressGestureRecognizer *)gestureRecognizer
    if (gestureRecognizer.state != UIGestureRecognizerStateEnded) 
        return;
    
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Gesture:" message:@"hold it" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];

不确定这是否会产生任何影响，但图像视图是稍后以编程方式创建的，而不是在加载时创建的。提前感谢您的任何帮助..

另外，我查看了以下链接：

Long press gesture on UICollectionViewCell

Long press gesture recognizer on UIButton?

Apple Link 1

Apple Link 2

【问题讨论】：

您在哪里向 imageView 添加手势？我只能看到处理程序方法

我的错误......在viewDidLoad中。谢谢。

【参考方案1】：

-(void)viewDidLoad

    [super viewDidLoad];
    [self setupGesture];


-(void) setupGesture

    UILongPressGestureRecognizer *lpHandler = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleHoldGesture:)];
    lpHandler.minimumPressDuration = 1; //seconds
    lpHandler.delegate = self;
    //myUIImageViewInstance - replace for your instance/variable name
    [**myUIImageViewInstance** addGestureRecognizer:lpHandler];


- (void) handleHoldGesture:(UILongPressGestureRecognizer *)gesture

   if(UIGestureRecognizerStateBegan == gesture.state)
   
        // Called on start of gesture, do work here
   

   if(UIGestureRecognizerStateChanged == gesture.state)
   
        // Do repeated work here (repeats continuously) while finger is down
   

   if(UIGestureRecognizerStateEnded == gesture.state)
   
        // Do end work here when finger is lifted
   

【讨论】：

仍然不适合我...我的图像是 22x22 是否重要？

我不这么认为。检查适当的 userInteractionEnabled，应为 YES (true) 基于类参考： userInteractionEnabled 一个布尔值，确定是否忽略用户事件并将其从事件队列中删除。 @property(nonatomic, getter=isUserInteractionEnabled) BOOL userInteractionEnabled 讨论 该属性继承自 UIView 父类。此类将此属性的默认值更改为 NO。

为我工作而无需添加行 lpHandler.delegate = self;

对我不起作用，最好遵循这个解决方案：***.com/a/34548629/4994239

【参考方案2】：

UIImageViews 默认有userInteractionEnabled = NO。如果您将手势识别器添加到 UIImageView 的实例中，请确保将其设置回 YES：myImageView.userInteractionEnabled = YES