ios - 使用 UIGestureRecogniser 子类化时未调用 Touches Ended

Question

我正在尝试为我的 View 创建自定义手势识别器。我正在关注这里提到的这个答案:但由于某种原因，没有调用已触摸的 Ended 和已拍摄的触摸。只有触摸开始才会被调用。

子类:

#import "TapGesture.h"
#import <UIKit/UIGestureRecognizerSubclass.h>

@implementation TapGesture

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    if (self.state == UIGestureRecognizerStatePossible) {
        self.state = UIGestureRecognizerStateRecognized;
    }
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{
    self.state = UIGestureRecognizerStateFailed;
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
    self.state = UIGestureRecognizerStateFailed;
}

-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{

}

@end

我正在按如下方式初始化 TapGesture:

TapGesture *tapGesture=[[TapGesture alloc]initWithTarget:self action:@selector(incrementValue)];
tapGesture.delaysTouchesEnded=NO;
tapGesture.cancelsTouchesInView=NO;
[_workButton addGestureRecognizer:tapGesture]; //_workButton is a UIView

我在 View 中没有任何其他手势识别器。如果我在 UIView 中使用相同的方法，所有这些方法都会按预期调用。

为什么在 UIGestureRecogniser 类中覆盖时没有调用 touchesEnded/touchesMoved？

Answer 1

当子类化 UIGestureRecognizer 时，您必须使其表现得像一个连续 手势并由您自己处理它的状态机(即，手动设置它的状态 ).

来自 UIGestureRecognizer 上的 iOS 开发者库文档:

Subclasses must set the state property to the appropriate value when they transition between states.

See here for more info (向下滚动到子类注释)

• 注意:要使 state 可读/可写，而不是只读，您应该使用 UIGestureRecognizerSubclass.h，如文档中所述:

  The state property is declared in UIGestureRecognizer.h as being read-only. This property declaration is intended for clients of gesture recognizers. Subclasses of UIGestureRecognizer must import UIGestureRecognizerSubclass.h. This header file contains a redeclaration of state that makes it read-write.