将UIMapGestureRecognizer直接实现到UIView而不是ViewController中是不起作用的

Question

正如在这个SO答案中所解释的，我正试图在UIIMageView的子类中实现UITapGestureRecognizer。我的方法可以在下面找到。

MenuButtonImageView的一个实例是homeScreenViewController.view的一个子视图。

我还实现了touchesBegan:withEvent:、touchesMoved:withEvent:和touchesEnded:withEvent:，并且做得很好。

问题：不知何故，handleSingleFingeredTap:从未被调用。这可能有什么问题？

@interface MenuButtonImageView : UIImageView
@property (nonatomic, weak) IBOutlet HomescreenViewController *homeScreenViewController;
@property (nonatomic, readwrite) Visibility visibility;
- (void)handleSingleFingeredTap:(UITapGestureRecognizer *)recognizer;
@end
@implementation MenuButtonImageView
- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        self.visibility = HIDDEN;
        self.userInteractionEnabled = YES;
        UITapGestureRecognizer * singleFingeredTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleFingeredTap:)];
        singleFingeredTap.numberOfTapsRequired = 1;
        [self addGestureRecognizer:singleFingeredTap];
    }
    return self;
}
- (void)handleSingleFingeredTap:(UITapGestureRecognizer *)recognizer {
    NSLog(@"handleTap was called"); // This method is not called!
    [self toggleMainMenu];
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { ... }
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event { ... }
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event { ... }
@end

Answer 1

在initWithFrame方法中添加识别器。检查您的视图是否以这种方式初始化。它可能是用另一个构造函数（如initWithCoder）创建的，然后您的代码就不执行了。在initWithFrame方法中放置一个断点来查找。

您可以将代码放在一个单独的方法中，并从两个构造函数中调用它。这取决于你如何使用它。当你从代码中创建视图时，initWithFrame的使用非常常见。