swift - 拖动 map View 时停止更新位置

Question

我有一个 map View ，其中包含他的更新位置。因此，如果我移动，我的定位会不断更新。如果我拖动 map 并尝试在其上查看其他内容，我希望它停止。我该怎么做？

我试过这个解决方案，来检测 map 何时被拖动: Determine if MKMapView was dragged/moved in Swift 2.0

我在 swift3 工作。

1:在viewDidLoad中添加手势识别器:

    let mapDragRecognizer = UIPanGestureRecognizer(target: self, action: Selector(("didDragMap:")))
    mapDragRecognizer.delegate = self
    self.map.addGestureRecognizer(mapDragRecognizer)

2:将协议(protocol) UIGestureRecognizerDelegate 添加到 View Controller ，使其作为委托(delegate)工作。

 class MapViewController: UIViewController, UIGestureRecognizerDelegate

1. 添加了其他代码:

   func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
   return true
   }
   
     func didDragMap(gestureRecognizer: UIGestureRecognizer) {
   if (gestureRecognizer.state == UIGestureRecognizerState.began) {
       print("Map drag began")
     self.locationManager.stopUpdatingLocation()
       }
   
   if (gestureRecognizer.state == UIGestureRecognizerState.ended) {
       print("Map drag ended")
   }
   }
   

如果我拖动 map ，应用程序会崩溃。我得到了这个:“由于未捕获的异常‘NSInvalidArgumentException’而终止应用程序，原因:‘-[app.ViewController didDragMap:]: 无法识别的选择器发送到实例 0x7fdf1fd132c0’”(..)“libc++abi.dylib:以 NSException 类型的未捕获异常终止"

Answer 1

Swift 3 中的选择器语法发生了变化。您的手势识别器现在应该如下所示:

let mapDragRecognizer = UIPanGestureRecognizer(target: self, action: #selector(didDragMap))

func didDragMap(_ gestureRecognizer: UIGestureRecognizer) {
   if (gestureRecognizer.state == UIGestureRecognizerState.began) {
       print("Map drag began")
       self.locationManager.stopUpdatingLocation()
   }
   if (gestureRecognizer.state == UIGestureRecognizerState.ended) {
       print("Map drag ended")
   }
}

注意 didDragMap(_:) 是根据新的 Swift API Design Guidelines 声明的

我还会用 switch 语句替换你的 if 语句，因为一旦有两种以上的情况，编译器就能够更好地优化它，而且更清楚.即

func didDragMap(_ gestureRecognizer: UIGestureRecognizer) {
    switch gestureRecognizer.state {
    case .began:
        print("Map drag began")
        self.locationManager.stopUpdatingLocation()

    case .ended:
        print("Map drag ended")

    default:
        break
    }
}