如何检测在 Swift 中移动的 mapView 并更新缩放

Question

我正在尝试在 Swift 2 中在我的地图上设置最小缩放级别。我找不到任何关于如何限制地图被放大得太远的文档。我决定尝试的是监视地图移动（例如拖动或缩放）然后设置MKZoomScale回最小值。

我找到的大多数答案regionDidChangeAnimated都在 Objective C 中，我不知道，而且我无法将它们转换为 Swift。

我尝试实现@hEADcRASH 的答案：https ://stackoverflow.com/a/30924768/4106552 ，但是当地图在模拟器中移动时，它不会触发并打印任何内容到控制台。

谁能告诉我我做错了什么？我是 Swift 的新手，所以这可能是一个小错误。另外，让我知道是否有一种轻量级的方法来解决限制地图上的缩放级别。我担心运动监视器会稍微减慢地图动画的速度。谢谢您的帮助。

这是我的视图控制器。导入 UIKit 导入解析导入 MapKit

class SearchRadiusViewController: UIViewController, CLLocationManagerDelegate, MKMapViewDelegate {

@IBOutlet weak var map: MKMapView!

@IBOutlet weak var menuBtn: UIBarButtonItem!

var locationManager = CLLocationManager()

override func viewDidLoad() {
    super.viewDidLoad()

    //menu button control
    if self.revealViewController() != nil {
        menuBtn.target = self.revealViewController()
        menuBtn.action = "revealToggle:"
        self.view.addGestureRecognizer(self.revealViewController().panGestureRecognizer())
    }

    //user location
    locationManager.delegate = self
    locationManager.desiredAccuracy = kCLLocationAccuracyBest
    locationManager.requestWhenInUseAuthorization()
    locationManager.startUpdatingLocation()


}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

    //set map
    let location:CLLocationCoordinate2D = manager.location!.coordinate
    let latitude = location.latitude
    let longitude = location.longitude
    let latDelta:CLLocationDegrees = 0.1
    let longDelta:CLLocationDegrees = 0.1
    let span:MKCoordinateSpan = MKCoordinateSpanMake(latDelta, longDelta)
    let maplocation:CLLocationCoordinate2D = CLLocationCoordinate2DMake(latitude, longitude)
    let region:MKCoordinateRegion = MKCoordinateRegionMake(maplocation, span)
    map.setRegion(region, animated: true)

    //stop updating location, only need user location once to position map.
    manager.stopUpdatingLocation()

}

//Attempt to monitor for map movement based on hEADcRASH's answer.
private var mapChangedFromUserInteraction = false

private func mapViewRegionDidChangeFromUserInteraction() -> Bool {
    let view = self.map.subviews[0]
    //  Look through gesture recognizers to determine whether this region change is from user interaction
    if let gestureRecognizers = view.gestureRecognizers {
        for recognizer in gestureRecognizers {
            if( recognizer.state == UIGestureRecognizerState.Began || recognizer.state == UIGestureRecognizerState.Ended ) {
                return true
            }
        }
    }
    return false
}

func mapView(mapView: MKMapView, regionWillChangeAnimated animated: Bool) {
    print("yes")
    mapChangedFromUserInteraction = mapViewRegionDidChangeFromUserInteraction()
    if (mapChangedFromUserInteraction) {
        // user changed map region
        print("user changed map in WILL")
    }
}

func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
            print("yes ddd")
    if (mapChangedFromUserInteraction) {
        // user changed map region
        print("user changed map in Did")
    }
}
}

Answer 1

在查看并结合了许多其他问题/答案以及@lorenzoliveto 的帮助后，我已经在 Swift 中使用了它。如果有更好/更轻量级的方法来实现同样的目标，请发表评论。

我添加self.map.delegate = self到 viewDidLoad 函数。

下面是我如何监控地图移动的代码，然后一旦用户放大“太远”并且地图的宽度低于 2 英里，我就会使用mapView.setRegion.

private var mapChangedFromUserInteraction = false

private func mapViewRegionDidChangeFromUserInteraction() -> Bool {
    let view = self.map.subviews[0]
    //  Look through gesture recognizers to determine whether this region change is from user interaction
    if let gestureRecognizers = view.gestureRecognizers {
        for recognizer in gestureRecognizers {
            if( recognizer.state == UIGestureRecognizerState.Began || recognizer.state == UIGestureRecognizerState.Ended ) {
                return true
            }
        }
    }
    return false
}

func mapView(mapView: MKMapView, regionWillChangeAnimated animated: Bool) {
    mapChangedFromUserInteraction = mapViewRegionDidChangeFromUserInteraction()
    if (mapChangedFromUserInteraction) {
        // user will change map region
        print("user WILL change map.")

        // calculate the width of the map in miles.
        let mRect: MKMapRect = mapView.visibleMapRect
        let eastMapPoint = MKMapPointMake(MKMapRectGetMinX(mRect), MKMapRectGetMidY(mRect))
        let westMapPoint = MKMapPointMake(MKMapRectGetMaxX(mRect), MKMapRectGetMidY(mRect))
        let currentDistWideInMeters = MKMetersBetweenMapPoints(eastMapPoint, westMapPoint)
        let milesWide = currentDistWideInMeters / 1609.34  // number of meters in a mile
        print(milesWide)
        print("^miles wide")

        // check if user zoomed in too far and zoom them out.
        if milesWide < 2.0 {
            var region:MKCoordinateRegion = mapView.region
            var span:MKCoordinateSpan = mapView.region.span
            span.latitudeDelta = 0.04
            span.longitudeDelta = 0.04
            region.span = span;
            mapView.setRegion(region, animated: true)
            print("map zoomed back out")
        }

    }
}

func mapView(mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
    if (mapChangedFromUserInteraction) {
        // user changed map region
        print("user CHANGED map.")
        print(mapView.region.span.latitudeDelta)
        print(mapView.region.span.longitudeDelta)

        // calculate the width of the map in miles.
        let mRect: MKMapRect = mapView.visibleMapRect
        let eastMapPoint = MKMapPointMake(MKMapRectGetMinX(mRect), MKMapRectGetMidY(mRect))
        let westMapPoint = MKMapPointMake(MKMapRectGetMaxX(mRect), MKMapRectGetMidY(mRect))
        let currentDistWideInMeters = MKMetersBetweenMapPoints(eastMapPoint, westMapPoint)
        let milesWide = currentDistWideInMeters / 1609.34  // number of meters in a mile
        print(milesWide)
        print("^miles wide")

        // check if user zoomed in too far and zoom them out.
        if milesWide < 2.0 {
            var region:MKCoordinateRegion = mapView.region
            var span:MKCoordinateSpan = mapView.region.span
            span.latitudeDelta = 0.04
            span.longitudeDelta = 0.04
            region.span = span;
            mapView.setRegion(region, animated: true)
            print("map zoomed back out")
        }
    }

更新：3/7，我在上面的实现中发现了一个有趣的错误。在模拟器上，单击缩放时它可以正常工作，但是当您使用捏合缩放（选项 + 单击）时，模拟器停止允许您在动画缩小后拖动地图。这也发生在我的 iphone 测试版上。我dispatch_async在使地图回到它们的位置的动画块周围添加了它，它似乎在模拟器上工作。它在动画后不再出现冻结，我可以继续在地图上拖动并尝试放大。

dispatch_async(dispatch_get_main_queue(), {
   var region:MKCoordinateRegion = mapView.region
   var span:MKCoordinateSpan = mapView.region.span
   span.latitudeDelta = 0.04
   span.longitudeDelta = 0.04
   region.span = span;
   mapView.setRegion(region, animated: true)
   print("map zoomed back out")
})