将MKMapRect转换为CGRect

Question

我正在试图找出MKMapRect的大小(即iPhone的320x568点)。

是否有类似于将协调点转换为点的东西？即

[self.mapView convertCoordinate:coordinate1 toPointToView:self.view];

Answer 1

映射视图具有convertRegion:toRectToView:方法，该方法接受MKCoordinateRegion并将其转换为相对于指定视图的CGRect。

如果您有一个MKMapRect，首先使用MKCoordinateRegionForMapRect函数将其转换为MKCoordinateRegion，然后调用convertRegion:toRectToView:。

示例：

MKCoordinateRegion mkcr = MKCoordinateRegionForMapRect(someMKMapRect);

CGRect cgr = [mapView convertRegion:mkcr toRectToView:self.view];

请记住，虽然某些固定区域的MKMapRect不会随着地图的缩放或平移而改变，但对应的CGRect将在其origin和size中发生变化。

Answer 2

也许作为一个实际例子..。我使用这段代码向屏幕上的地图添加一个覆盖层，然后检查屏幕的哪个部分是否需要更新。

此方法是MKOverlay类的一部分。我的UIViewController名为"MyWaysViewController“，屏幕上的映射名为"MapOnScreen”(只是为了理解代码)。

它的Swift 3/ IOS 10代码

/**
 -----------------------------------------------------------------------------------------------

 adds the overlay to the map and sets "setNeedsDisplay()" for the visible part of the overlay

 -----------------------------------------------------------------------------------------------

 - Parameters:

 - Returns: nothing

 */
func switchOverlayON() {

    DispatchQueue.main.async(execute: {
        // add the new overlay

        // if the ViewController is already initialised
        if MyWaysViewController != nil {

            // add the overlay
            MyWaysViewController!.MapOnScreen.add(self)

            // as we are good citizens on that device, we check if and for what region we setNeedsDisplay()

            // get the intersection of the overlay and the visible region of the map
            let visibleRectOfOverlayMK = MKMapRectIntersection(
                    self.boundingMapRect,
                    MyWaysViewController!.MapOnScreen.visibleMapRect
            )

            // check if it is null (no intersection -> not visible at the moment)
            if MKMapRectIsNull(visibleRectOfOverlayMK) == false {

                // It is not null, so at least parts are visible, now a two steps aproach to
                // convert MKMapRect to cgRect. first step: get a coordinate region
                let visibleRectCoordinateRegion = MKCoordinateRegionForMapRect(visibleRectOfOverlayMK)

                // second step, convert the region to a cgRect
                let visibleRectOfOverlayCG = MyWaysViewController!.MapOnScreen.convertRegion(visibleRectCoordinateRegion, toRectTo: MyWaysViewController!.MapOnScreen)

                // ask to refresh that cgRect
                MyWaysViewController!.MapOnScreen.setNeedsDisplay(visibleRectOfOverlayCG)
            }
        }
    })
}