iOS 事件处理指南说:"有时您可能希望视图在手势识别器之前接收触摸",但我找不到如何做到这一点。
我尝试了延迟触摸结束 = 假,但它没有任何效果。
@IBOutlet weak var myPickerView: UIPickerView!
override func viewDidLoad() {
super.viewDidLoad()
let tapGesture:UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(MyViewController.pickerViewTapped(_:)))
tapGesture.delegate = self
tapGesture.delaysTouchesEnded = false
myPickerView.addGestureRecognizer(tapGesture)
}
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int){
// called by UIPickerView
print("pickerView called!")
}
func pickerViewTapped(_ sender: UITapGestureRecognizer) {
// called by UITapGestureRecognizer
print("pickerViewTapped called!")
}
当我点击myPickerView时,控制台将是
pickerViewTapped called!
pickerView called!
但我希望它们以相反的顺序排列。怎么做?
简短回答:
您不能仅使用 UIGestureRecognizer 来执行此操作。
长答案:
由于将行移动到UIPickerView本身的中心需要动画,因此在选择UIPickerView的行的操作和方法didSelectRow
的调用之间总是存在延迟。
另请注意,如果点击中心的行,则不会调用 didSelectRow
方法,而只会调用pickerViewTapped
方法。
这种延迟必然会使执行序列:
-
pickerViewTapped
-
pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int){
我找到的解决方案是这样的:
func pickerViewTapped(_ sender: UITapGestureRecognizer) {
// called by UITapGestureRecognizer
let timeDelay = 0.6
//0.6 is arbitrary value, depends on you
DispatchQueue.main.asyncAfter(deadline: .now() + timeDelay) {
print("pickerViewTapped called!")
}
}
我知道也许这不是你要找的答案,我也不知道你为什么会有这样的行为,但这是我找到的最接近的解决方案。