我正在检测用户是否按下了 2 秒:
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
initWithTarget:self
action:@selector(handleLongPress:)];
longPress.minimumPressDuration = 2.0;
[self addGestureRecognizer:longPress];
[longPress release];
这就是我处理长按的方式:
-(void)handleLongPress:(UILongPressGestureRecognizer*)recognizer{
NSLog(@"double oo");
}
当我按下超过 2 秒时,文本“double oo”会打印两次。为什么是这样?我该如何解决?
UILongPressGestureRecognizer 是一个连续事件识别器。您必须查看状态,看看这是事件的开始、中间还是结束,并采取相应的行动。即,您可以在开始后丢弃所有事件,或者仅根据需要查看运动。从 Class Reference:
长按手势是连续的。当允许的手指数量 (numberOfTouchesRequired) 在指定的时间 (minimumPressDuration) 内被按下并且触摸没有超出允许的移动范围 (allowableMovement) 时,手势开始 (UIGestureRecognizerStateBegan)。每当手指移动时,手势识别器就会转换到 Change 状态,并在任何手指抬起时结束 (UIGestureRecognizerStateEnded)。
现在您可以像这样跟踪状态
- (void)handleLongPress:(UILongPressGestureRecognizer*)sender {
if (sender.state == UIGestureRecognizerStateEnded) {
NSLog(@"UIGestureRecognizerStateEnded");
//Do Whatever You want on End of Gesture
}
else if (sender.state == UIGestureRecognizerStateBegan){
NSLog(@"UIGestureRecognizerStateBegan.");
//Do Whatever You want on Began of Gesture
}
}
要检查 UILongPressGestureRecognizer 的状态,只需在选择器方法上添加一个 if 语句:
- (void)handleLongPress:(UILongPressGestureRecognizer *)sender {
if (sender.state == UIGestureRecognizerStateEnded) {
NSLog(@"Long press Ended");
} else if (sender.state == UIGestureRecognizerStateBegan) {
NSLog(@"Long press detected.");
}
}
您需要检查正确的状态,因为每个状态都有不同的行为。您很可能需要带有 UILongPressGestureRecognizer
的 UIGestureRecognizerStateBegan
状态。
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
initWithTarget:self
action:@selector(handleLongPress:)];
longPress.minimumPressDuration = 1.0;
[myView addGestureRecognizer:longPress];
[longPress release];
...
- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
if(UIGestureRecognizerStateBegan == gesture.state) {
// Called on start of gesture, do work here
}
if(UIGestureRecognizerStateChanged == gesture.state) {
// Do repeated work here (repeats continuously) while finger is down
}
if(UIGestureRecognizerStateEnded == gesture.state) {
// Do end work here when finger is lifted
}
}
试试这个:
Objective-C
- (void)handleLongPress:(UILongPressGestureRecognizer*)sender {
if (sender.state == UIGestureRecognizerStateEnded) {
NSLog(@"Long press Ended");
} else if (sender.state == UIGestureRecognizerStateBegan) {
NSLog(@"Long press detected.");
}
}
斯威夫特 2.2:
func handleLongPress(sender:UILongPressGestureRecognizer) {
if (sender.state == UIGestureRecognizerState.Ended) {
print("Long press Ended");
} else if (sender.state == UIGestureRecognizerState.Began) {
print("Long press detected.");
}
}
斯威夫特 3.0:
func handleLongPress(sender: UILongPressGestureRecognizer) {
if sender.state == .ended {
print("Long press Ended")
} else if sender.state == .began {
print("Long press detected")
}
以下是在 Swift 中处理它的方法:
func longPress(sender:UILongPressGestureRecognizer!) {
if (sender.state == UIGestureRecognizerState.Ended) {
println("Long press Ended");
} else if (sender.state == UIGestureRecognizerState.Began) {
println("Long press detected.");
}
}
您的手势处理程序接收每个手势状态的调用。所以您需要检查每个状态并将您的代码置于所需状态。
必须更喜欢使用 switch-case 而不是 if-else :
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
initWithTarget:self
action:@selector(handleLongPress:)];
longPress.minimumPressDuration = 1.0;
[myView addGestureRecognizer:longPress];
[longPress release];
-(void)handleLongPress:(UILongPressGestureRecognizer *)gesture {
switch(gesture.state){
case UIGestureRecognizerStateBegan:
NSLog(@"State Began");
break;
case UIGestureRecognizerStateChanged:
NSLog(@"State changed");
break;
case UIGestureRecognizerStateEnded:
NSLog(@"State End");
break;
default:
break;
}
}
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