UIGestureRecognizer不工作

Question

我不确定我做错了什么，但这里有一个简化的例子：

@interface Test : NSObject<UIGestureRecognizerDelegate> {
    UIView *_someParentView;
    UIView *_someChildView;
}
- (id)initWithParentView:(UIView *)parentView;
@end

@implementation Test

- (id)initWithParentView:(UIView *)parentView
{
    if (self = [super init])
    {
        _someParentView = parentView;
    }
    return self;
}

- (void)addSubViewsWhenReady
{
    _someChildView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    _someChildView.backgroundColor = [UIColor blackColor];
    [_someChildView setUserInteractionEnabled:YES];
    [_someParentView addSubview:_someChildView];

    UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
    singleFingerTap.delegate = self;
    [_someChildView addGestureRecognizer:singleFingerTap];
}

- (void)handleSingleTap:(id)sender
{
    NSLog(@"handle the single tap");
}

@end

输出：“处理单击”永远不会被记录下来。你知道我做错了什么吗？

谢谢!

Answer 1

像你这样设定目标：

UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];

是你的问题。如果这里的"self“是一个UIViewController，它将会工作。

即

@interface Test : UIViewController<UIGestureRecognizerDelegate> {
    UIView *_someParentView;
    UIView *_someChildView;
}
- (id)initWithParentView:(UIView *)parentView;
@end

@implementation Test

- (id)initWithParentView:(UIView *)parentView
{
    if (self = [super init])
    {
        _someParentView = parentView;
    }
    return self;
}

- (void)addSubViewsWhenReady
{
    _someChildView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];
    _someChildView.backgroundColor = [UIColor blackColor];
    [_someChildView setUserInteractionEnabled:YES];
    [_someParentView addSubview:_someChildView];

    UITapGestureRecognizer *singleFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
    singleFingerTap.delegate = self;
    [_someChildView addGestureRecognizer:singleFingerTap];
}

- (void)handleSingleTap:(UIGestureRecognizer*)recognizer    {
    NSLog(@"handle the single tap");
}

@end

Answer 2

尝试将handleSingleTap:的定义更改为

- (void)handleSingleTap:(UIGestureRecognizer*)recognizer {
    NSLog(@"handle the single tap");
}

从UIGestureRecognizer文档中：

手势识别器有一个或多个与之关联的目标-动作对。如果有多个目标-动作对，则它们是离散的，而不是累积的。对手势的识别导致向这些对中的每一个的目标发送动作消息。调用的操作方法必须符合以下签名之一：

- (void)handleGesture;

- (void)handleGesture:(UIGestureRecognizer *)gestureRecognizer;