Question

今天我遇到一些奇怪的事情，同时将相同的手势识别器附加到多个图像视图。它仅附加到最后一个，换句话说，它只能附加到一个视图！

我必须创建多个手势识别器才能满足我的要求。

以下是我所做的。我做得对吗？这是将识别器附加到多个图像视图的唯一方法吗？

请注意，我不想使用UITableView或UIVIew并将所有图像视图放入其中，并仅将手势识别器附加到UITableView或UIVIew。我将所有图像分散，我必须检测正在拖动的图像。感谢。

[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 action:@selector(gestureHandler:)];
gestureRecognizer1.delegate = self;

gestureRecognizer2 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gestureHandler:)];
gestureRecognizer2.delegate = self;

gestureRecognizer3 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gestureHandler:)];
gestureRecognizer3.delegate = self;

gestureRecognizer4 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gestureHandler:)];
gestureRecognizer4.delegate = self;

gestureRecognizer5 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gestureHandler:)];
gestureRecognizer5.delegate = self;

gestureRecognizer6 = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gestureHandler:)];
gestureRecognizer6.delegate = self;

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

Answer 1

您无法将手势识别器附加到多个对象（如您所发现的那样）。您正在做的一个解决方案可能是子类UIImageView并在该类中设置代码，以便每个视图创建其识别器等。

Answer 2

是的，每个手势识别器有一个视图。因此，如果您只想要一个识别器，请将其放在超级视图上，例如：

UILongPressGestureRecognizer *gestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gestureHandler:)];
[self.view addGestureRecognizer:gestureRecognizer];

然后，在你的处理程序中，你可以：

- (void)handleLongPress:(UILongPressGestureRecognizer *)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，你也不必担心在图像上启用用户交互。

最后，除非你要遵守UIGestureRecognizerDelegate，否则你不必担心指定你的手势识别器的委托。另请注意，我正在使用本地var作为识别器，因为没有理由坚持它。

<强>更新

虽然上面的代码工作得很好，但是如果长按没有在图像上发生，那么自定义的长按手势识别器可能会更好（这样一来，如果你有其他的话，它更有可能发挥得很好在您的视图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)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)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你的手势识别器：

ImageLongPressGestureRecognizer *gestureRecognizer = [[ImageLongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
[self.view addGestureRecognizer:gestureRecognizer];

然后，作为这个子类化的一个很好的好处，你的主要手势识别器被简化，即：

- (void)handleLongPress:(ImageLongPressGestureRecognizer *)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];
                         }];
    }
}

Answer 3

我想，首先，你应该创建一个视图数组和识别器数组（如果需要的话，可变数组），然后填充它。它将帮助您使用循环来避免代码重复。

对于带有一个识别器的多视图 - 不，这是不可能的，answered here。

将GestureRecogniser附加到多个图像视图

3 个答案: