xcode 检测 UISlider 上的触摸？
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Detecting touches on a UISlider?
提问by Andrew Martin
I have a UISlider on screen, and I need to be able to detect when the user stops touching it. (so I can fade some elements away).
我在屏幕上有一个 UISlider，我需要能够检测到用户何时停止触摸它。（所以我可以淡化一些元素）。
I have tried using:
我试过使用：
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
but this did not work when ending touches on a slider.
但这在结束触摸滑块时不起作用。
回答by
You can detect when a touch ends using two control events; try
您可以使用两个控制事件检测触摸何时结束；尝试
[slider addTarget:self action:@selector(touchEnded:)
forControlEvents:UIControlEventTouchUpInside];
or
或者
[slider addTarget:self action:@selector(touchEnded:)
forControlEvents:UIControlEventTouchUpOutside];
If you want to detect both types of the touchesEndevent, use
如果要检测这两种类型的touchesEnd事件，请使用
[slider addTarget:self action:@selector(touchEnded:)
forControlEvents:UIControlEventTouchUpInside | UIControlEventTouchUpOutside];
回答by Evan Mulawski
Instead of using touchesEnded:(which shouldn't be used for this purpose anyway), attach an action to the UISlider's UIControlEventValueChangedevent and set the continuousproperty of the UISliderto NO, so the event will fire when the user finishes selecting a value.
不是使用touchesEnded:（无论如何都不应该用于此目的），而是将操作附加到UISlider的UIControlEventValueChanged事件并将 的continuous属性设置UISlider为NO，因此当用户完成选择值时将触发该事件。
mySlider.continuous = NO;
[mySlider addTarget:self
action:@selector(myMethodThatFadesObjects)
forControlEvents:UIControlEventValueChanged];
回答by Adrian
I couldn't get anything to capture both the start and end of the touches, but upon RTFD-ing, I came up with something that will do both.
我无法获得任何东西来捕捉触摸的开始和结束，但是在 RTFD 中，我想出了一些可以同时做到的东西。
@IBAction func sliderAction(_ sender: UISlider, forEvent event: UIEvent) {
if let touchEvent = event.allTouches?.first {
switch touchEvent.phase {
case .began:
print("touches began")
sliderTouchBegan()
case .ended:
print("touches ended")
sliderTouchEnded()
default:
delegate?.sliderValueUpdated(sender.value)
}
}
}
sliderTouchBegan()and sliderTouchEnded()are just methods I wrote that handle animations when the touch begins and when it ends. If it's not a begin or end, it's a defaultand the slider value updates.
sliderTouchBegan()并且sliderTouchEnded()只是我编写的处理触摸开始和结束时的动画的方法。如果它不是开始或结束，则是 adefault并且滑块值会更新。
