我有非常简单的视图控制器来演示 MKPolyline 这种奇怪的渲染行为。没什么特别的,只是普通的 api 调用。
import UIKit
import MapKit
class ViewController: UIViewController, MKMapViewDelegate {
@IBOutlet weak var map: MKMapView!
override func viewDidLoad() {
super.viewDidLoad()
map.delegate = self
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
let p1 = CLLocationCoordinate2D(latitude: 51, longitude: 13)
var coords = [
p1,
CLLocationCoordinate2D(latitude: 51.1, longitude: 13),
CLLocationCoordinate2D(latitude: 51.2, longitude: 13),
CLLocationCoordinate2D(latitude: 51.3, longitude: 13)
]
let polyline = MKPolyline(coordinates: &coords, count: coords.count)
map.addOverlays([polyline], level: .aboveRoads)
let cam = MKMapCamera(lookingAtCenter: p1, fromDistance: 1000, pitch: 45, heading: 0)
map.setCamera(cam, animated: true)
}
func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
let r = MKPolylineRenderer(overlay: overlay)
r.strokeColor = UIColor.blue
return r
}
}
折线的渲染很奇怪。在缩放和平移过程中,您可能会看到一些伪影。
看看下面的图片:
Initial Screen
After some panning
After zooming out and zooming in again
如何解决这个问题?我试图实现我自己的渲染器,但情况相同。就像 overaly 被缓存一样,它没有按时重绘。我正在使用 iOS 10、iPhone 6、iOS SDK 10 xCode 8 的模拟器。