OStack程序员社区-中国程序员成长平台

标题: ios - 将 GestureRecogniser 附加到多个 ImageView [打印本页]

---

作者: 菜鸟教程小白    时间: 2022-12-12 21:50
标题: ios - 将 GestureRecogniser 附加到多个 ImageView

我今天在将同一个手势识别器附加到多个 ImageView 时遇到了一些奇怪的事情。它只附加到最后一个，换句话说，它只能附加到一个 View !

我必须创建多个手势识别器来满足我的要求。

以下是我所做的。我做得对吗？这是将识别器附加到多个 ImageView 的唯一方法吗？

请注意，我不想使用 UITableView 或 UIVIew 并将所有 ImageView 放入其中并将手势识别器仅附加到 UITableView 或 UIVIew。我把所有图像都分散了，我必须检测哪个图像被拖动。谢谢。

[imgView1 setUserInteractionEnabled:YES];
[imgView1 setMultipleTouchEnabled:YES];

[imgView2 setUserInteractionEnabled:YES];
[imgView2 setMultipleTouchEnabled:YES];

[imgView3 setUserInteractionEnabled:YES];
[imgView3 setMultipleTouchEnabled:YES];

[imgView4 setUserInteractionEnabled:YES];
[imgView4 setMultipleTouchEnabled:YES];

[imgView5 setUserInteractionEnabled:YES];
[imgView5 setMultipleTouchEnabled:YES];

[imgView6 setUserInteractionEnabled:YES];
[imgView6 setMultipleTouchEnabled:YES];


//Attach gesture recognizer to each imagviews
gestureRecognizer1 = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
gestureRecognizer1.delegate = self;

gestureRecognizer2 = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
gestureRecognizer2.delegate = self;

gestureRecognizer3 = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
gestureRecognizer3.delegate = self;

gestureRecognizer4 = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
gestureRecognizer4.delegate = self;

gestureRecognizer5 = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
gestureRecognizer5.delegate = self;

gestureRecognizer6 = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
gestureRecognizer6.delegate = self;

[imgView1 addGestureRecognizer:gestureRecognizer1];
[imgView2 addGestureRecognizer:gestureRecognizer2];
[imgView3 addGestureRecognizer:gestureRecognizer3];
[imgView4 addGestureRecognizer:gestureRecognizer4];
[imgView5 addGestureRecognizer:gestureRecognizer5];
[imgView6 addGestureRecognizer:gestureRecognizer6];

---

Best Answer-推荐答案

是的，每个手势识别器一个 View 。因此，如果您只想要一个识别器，请将其放在 superview 上，例如:

UILongPressGestureRecognizer *gestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self actionselector(gestureHandler];
[self.view addGestureRecognizer:gestureRecognizer];

然后，在您的处理程序中，您可以:

- (void)handleLongPressUILongPressGestureRecognizer *)sender
{
    CGPoint location = [sender locationInView:self.view];

    if (sender.state == UIGestureRecognizerStateBegan)
    {
        for (UIView *view in self.view.subviews)
        {
            if ([view isKindOfClass:[UIImageView class]] && CGRectContainsPoint(view.frame, location))
            {
                UIImageView *image = (UIImageView *) view;

                // ok, now you know which image you received your long press for
                // do whatever you wanted on it at this point

                return;
            }
        }
    }
}

顺便说一句，如果你这样做了，你也不必担心在图像上启用用户交互。

最后，您无需担心指定手势识别器的委托(delegate)，除非您要遵守 UIGestureRecognizerDelegate，但事实并非如此。另请注意，我使用本地 var 作为识别器，因为没有理由坚持使用它。

更新:

虽然上面的代码可以正常工作，但如果长按没有发生在图像上，自定义长按手势识别器可能会更好(这样，如果您有其他在您的 View 中发生的手势识别器)。所以:

#import <UIKit/UIGestureRecognizerSubclass.h>

@interface ImageLongPressGestureRecognizer : UILongPressGestureRecognizer
@property (nonatomic, weak) UIImageView *imageview;
@end

@implementation ImageLongPressGestureRecognizer

@synthesize imageview = _imageview;

- (void)touchesBeganNSSet *)touches withEventUIEvent *)event
{
    self.imageview = nil;

    [super touchesBegan:touches withEvent:event];

    CGPoint location = [self locationInView:self.view];

    for (UIView *view in self.view.subviews)
    {
        if ([view isKindOfClass:[UIImageView class]] && CGRectContainsPoint(view.frame, location))
        {
            self.imageview = (UIImageView *)view;
            return;
        }
    }

    self.state = UIGestureRecognizerStateFailed;
}

@end

然后使用这个新的子类相应地创建您的手势识别器:

ImageLongPressGestureRecognizer *gestureRecognizer = [[ImageLongPressGestureRecognizer alloc] initWithTarget:self actionselector(handleLongPress];
[self.view addGestureRecognizer:gestureRecognizer];

然后，作为这个子类的一个不错的小好处，您的主要手势识别器被简化了，即:

- (void)handleLongPressImageLongPressGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateBegan)
    {
        // you can now do whatever you want with sender.imageview, e.g. this makes it blink for you:

        [UIView animateWithDuration:0.5 
                         animations:^{
                             sender.imageview.alpha = 0.0;
                         } completion:^(BOOL finished){
                             [UIView animateWithDuration:0.5 
                                              animations:^{
                                                  sender.imageview.alpha = 1.0;
                                              } 
                                              completion:nil];
                         }];
    }
}

关于ios - 将 GestureRecogniser 附加到多个 ImageView ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/11330738/

---

欢迎光临 OStack程序员社区-中国程序员成长平台 (https://ostack.cn/)

Powered by Discuz! X3.4