Swift - 当用户单击引脚注释时，使 MapView 标注注释可见答案

【问题标题】：Swift - Making MapView callout annotation visible when pin annotation clicked by UserSwift - 当用户单击引脚注释时，使 MapView 标注注释可见
【发布时间】：2017-02-22 18:37:38
【问题描述】：

请观察链接的图片（底部，下方）

当用户将地图屏幕移动到图钉最终靠近屏幕边缘的位置，然后选择该图钉注释时，Apple 方法随后将地图屏幕稍微移向屏幕中心，以便图钉注释标注可见。

我的问题有两个：

我。调用什么 Apple 方法来进行屏幕调整？

二。如果实现了 MKMapViewDelegate 扩展，那么在 mapView didSelect 视图方法中实现相同功能的最聪明的方法是什么？

Mapview屏幕调整顺序：

【问题讨论】：

标签： ios swift mkmapview mapkit mkmapviewdelegate

【解决方案1】：

理论上，你可以获取annotation view的frame并检查它是否离map view的边缘太近：

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    // if view.frame is too close to the edges of the MKMapView, triggered your desired method
}

实际上这是不可靠的，因为它还取决于注释视图的标注气泡。我们需要根据标注气泡的大小为“太靠近边缘”标准设置一个不同的阈值，对此没有简单的方法。

这有点hacky：当屏幕调整时，regionWillChangeAnimated 方法会被调用。如果它在点击注释的瞬间触发，则很有可能是由用户点击注释引起的：

weak var tappedAnnotationView: MKAnnotationView?

func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
    self.tappedAnnotationView = view // this property will only be non-nil for 0.1 seconds
    DispatchQueue.global().asyncAfter(deadline: .now() + 0.1) {
        self.tappedAnnotationView = nil
    }
}

func mapView(_ mapView: MKMapView, regionWillChangeAnimated animated: Bool) {
    if self.tappedAnnotationView != nil {
        print("map adjusted due to tap on an annotation view")
    }
}

它适用于我对其进行的基本测试，但由于它是一个 hack，因此显然会出现极端情况。

【讨论】：

感谢您抽出宝贵时间回复。我很感激。

【解决方案2】：

我想出的是以下内容：

 func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {

    // Get Coordinate for Selected Map Pin
    let selectedPinCoordinate = (view.annotation?.coordinate)!

    // Determine (X,Y) coordinates for Selected Map Pin on view (mapView)
    let SelectedPinMapPoint = mapView.convert(selectedPinCoordinate, toPointTo: mapView)

    // Determine (X,Y) coordinate for center point of view (mapView)
    let mapCenterMapPoint = mapView.convert(mapView.centerCoordinate, toPointTo: mapView)

    // Define an inner view within the existing view frame.  Any Selected Map Pin outside
    // bounds of inner view is deemed to be too close to the edge of the map for the callout
    // to be fully viewable by the user
    let innerRectFrameMinX = mapView.frame.maxX * 0.15
    let innerRectFrameMaxX = mapView.frame.maxX * 0.85
    let innerRectFrameMinY = mapView.frame.maxY * 0.30
    let innerRectFrameMaxY = mapView.frame.maxY * 0.85

    // Create a variable which will serve as the new center (X,Y) coordinate
    var newCenter = CGPoint()

    // Default new center (X,Y) coordinate to current view (X,Y) coordinate
    newCenter.x = mapCenterMapPoint.x
    newCenter.y = mapCenterMapPoint.y


    // Determine if x coordinate of Selected Map Pin is outside bounds. If so,
    // set a new center x coordinate so callout can be clearly seen by the user
    switch (SelectedPinMapPoint.x) {

    case _ where (SelectedPinMapPoint.x < innerRectFrameMinX):
        newCenter.x = mapView.frame.midX - (innerRectFrameMinX - SelectedPinMapPoint.x)

    case _ where (SelectedPinMapPoint.x > innerRectFrameMaxX):
        newCenter.x = mapView.frame.midX + (SelectedPinMapPoint.x - innerRectFrameMaxX)

    default: break

    }

    // Determine if y coordinate of Selected Map Pin is outside bounds. If so,
    // set a new center y coordinate so callout can be clearly seen by the user
    switch (SelectedPinMapPoint.y) {

    case _ where (SelectedPinMapPoint.y < innerRectFrameMinY):
        newCenter.y = mapView.frame.midY - (innerRectFrameMinY - SelectedPinMapPoint.y)

    case _ where (SelectedPinMapPoint.y > innerRectFrameMaxY):
        newCenter.y = mapView.frame.midY + (SelectedPinMapPoint.y - innerRectFrameMaxY)

    default: break

    }

   // Convert new map Center (X,Y) coordinate to map coordinate
   let newCenterCoordinate = mapView.convert(newCenter, toCoordinateFrom: nil)

   // Set new center as center for map view
   mapView.setCenter(newCenterCoordinate, animated: true)

}

我已经链接了我的概念的粗略图形草图，无论它可能提供什么好处。Rough Graphical Sketch

【讨论】：