• 百度地图
• 高德地图
• 腾讯地图
• 原生地图

三方地图框架的确很便捷，为我们封装了很多好用功能， 比如连最基础的地图缩放等级，在源生地图中默认也是不包含的

境外统一为 WGS84， 国内高德与腾讯使用的是国测局的 GCJ02， 百度是二次加密后的 BD09

最常见的三个坐标系，除此之外，还有其他坐标系

地图覆盖物主要包含以下两类

• Annotation
• Overlay

Annotation 基本做地图必用的， 展示一些自定义样式大头针
Overlay 包含路线、图形等，以及一些手绘图自定义图片等

Overlay 其主要包含

• MKPolyline: 比如路线
• MKPolygon: 比如绘制矩形、不规则多边形等
• MKCircle: 绘制圆形

自定义图片覆盖物可以通过自定义 Overlay 实现

• e.g. 绘制矩形

  let southWest = CLLocationCoordinate2D(latitude: 39.912804, longitude: 116.391462)
  let northEast = CLLocationCoordinate2D(latitude: 39.923593, longitude: 116.402614)
  
  let leftTop = CLLocationCoordinate2D(latitude: northEast.latitude, longitude: southWest.longitude)
  let leftDown = CLLocationCoordinate2D(latitude: southWest.latitude, longitude: southWest.longitude)
  let rightDown = CLLocationCoordinate2D(latitude: southWest.latitude, longitude: northEast.longitude)
  let rightTop = CLLocationCoordinate2D(latitude: northEast.latitude, longitude: northEast.longitude)
  
  /// 顺时针方向
  var coords = [leftTop, rightTop, rightDown, leftDown]
  
  /// 多边形
  let polygonOverlay = MKPolygon(coordinates: &coords, count: coords.count)
  mapView.addOverlay(polygonOverlay)

这里在设置坐标点时是顺时针方向， 之前在写百度地图绘制矩形时是传入了逆时针方向

效果图:

百度

• e.g. 图片覆盖物

  let centerLocation = CLLocation(latitude: 39.904685116866624, longitude: 116.3659296332766)
  let southWestLocation = CLLocation(latitude: 39.9042937397008, longitude: 116.36550672412181)
  let northEastLocation = CLLocation(latitude: 39.905045562412326, longitude: 116.36632992691236)
  
  /// 设置地图范围
  let latitudeDelta = northEastLocation.coordinate.latitude - southWestLocation.coordinate.latitude
  let longitudeDelta = northEastLocation.coordinate.longitude - southWestLocation.coordinate.longitude
  let span = MKCoordinateSpan(latitudeDelta: latitudeDelta, longitudeDelta: longitudeDelta)
  let region = MKCoordinateRegion(center: centerLocation.coordinate, span: span)
  mapView.setRegion(region, animated: true)
  
  /// 手绘图的区域
  let southWest = CLLocationCoordinate2D(latitude: southWestLocation.coordinate.latitude, longitude: southWestLocation.coordinate.longitude)
  let northEast = CLLocationCoordinate2D(latitude: northEastLocation.coordinate.latitude, longitude: northEastLocation.coordinate.longitude)
  
  let leftTop = CLLocationCoordinate2D(latitude: northEast.latitude, longitude: southWest.longitude)
  let leftDown = CLLocationCoordinate2D(latitude: southWest.latitude, longitude: southWest.longitude)
  let rightDown = CLLocationCoordinate2D(latitude: southWest.latitude, longitude: northEast.longitude)
  let rightTop = CLLocationCoordinate2D(latitude: northEast.latitude, longitude: northEast.longitude)
  
  /// 顺时针方向
  var coords = [leftTop, rightTop, rightDown, leftDown, leftTop]
  
  /// 地图中心点
  mapView.setCenter(centerLocation.coordinate, animated: true)
  
  if let overLay { mapView.removeOverlay(overLay) }
  
  groundImageName = "19585.jpg"
  let polygonOverlay = MKPolygon(coordinates: &coords, count: coords.count)
  overLay = polygonOverlay
  mapView.addOverlay(polygonOverlay)