MKMapView的状态恢复略微缩小
MKMapView的状态恢复略微缩小
提问于 2018-11-14 04:35:31
当恢复mapView的状态时，它会从保存时的位置略微缩小。我创建了一个iOS单视图应用程序，其中只包含一个填充整个视图的MKMapView，以尝试解决此问题。我的调试print语句显示，映射值被正确地保存和恢复，但是跨度、纬度或经度最终发生了变化。我遗漏了什么？
编辑：
此问题的主题与：
MKMapView setRegion "snaps" to predefined zoom levels?
MKMapView show incorrectly saved region
作为实验，我添加了一个MKCoordinateRegion类型的类变量，并将decodeRestorableState方法中读取的区域分配给它。此外，我还向视图控制器添加了一个按钮和操作处理程序，用于将mapView的区域设置为添加的变量的值。当点击按钮时，地图放大到恢复时所期望的位置。我感到奇怪的是，位置坐标在decodeRestorableState方法中不能正常工作，但在按钮的操作处理程序中，这些相同的坐标却能正常工作。
import UIKit
import MapKit
class ViewController: UIViewController {
@IBOutlet weak var mapView: MKMapView!
}
extension MKMapView {
override open func encodeRestorableState(with coder: NSCoder) {
super.encodeRestorableState(with: coder)
region.encodeRestorableState(with: coder)
camera.encodeRestorableState(with: coder)
}
override open func decodeRestorableState(with coder: NSCoder) {
super.decodeRestorableState(with: coder)
region.decodeRestorableState(with: coder)
camera.decodeRestorableState(with: coder)
}
}
extension MKCoordinateRegion {
private static let KEY_LATITUDE = "Region.latitude"
private static let KEY_LONGITUDE = "Region.longitude"
private static let KEY_WIDTH = "Region.spanWidth"
private static let KEY_HEIGHT = "Region.spanHeight"
func encodeRestorableState(with coder: NSCoder) {
coder.encode(center.latitude, forKey: MKCoordinateRegion.KEY_LATITUDE)
coder.encode(center.longitude, forKey: MKCoordinateRegion.KEY_LONGITUDE)
coder.encode(span.latitudeDelta, forKey: MKCoordinateRegion.KEY_HEIGHT)
coder.encode(span.longitudeDelta, forKey: MKCoordinateRegion.KEY_WIDTH)
}
mutating func decodeRestorableState(with coder: NSCoder) {
center.latitude = coder.decodeDouble(forKey: MKCoordinateRegion.KEY_LATITUDE)
center.longitude = coder.decodeDouble(forKey: MKCoordinateRegion.KEY_LONGITUDE)
span.latitudeDelta = coder.decodeDouble(forKey: MKCoordinateRegion.KEY_HEIGHT)
span.longitudeDelta = coder.decodeDouble(forKey: MKCoordinateRegion.KEY_WIDTH)
}
}
extension MKMapCamera {
private static let KEY_ALTITUDE = "Camera.altitude"
private static let KEY_HEADING = "Camera.heading"
private static let KEY_PITCH = "Camera.pitch"
private static let KEY_LATITUDE = "Camera.latitude"
private static let KEY_LONGITUDE = "Camera.longitude"
func encodeRestorableState(with coder: NSCoder) {
coder.encode(altitude, forKey: MKMapCamera.KEY_ALTITUDE)
coder.encode(heading, forKey: MKMapCamera.KEY_HEADING)
coder.encode(Double(pitch), forKey: MKMapCamera.KEY_PITCH)
coder.encode(centerCoordinate.latitude, forKey: MKMapCamera.KEY_LATITUDE)
coder.encode(centerCoordinate.longitude, forKey: MKMapCamera.KEY_LONGITUDE)
}
func decodeRestorableState(with coder: NSCoder) {
altitude = coder.decodeDouble(forKey: MKMapCamera.KEY_ALTITUDE)
heading = coder.decodeDouble(forKey: MKMapCamera.KEY_HEADING)
pitch = CGFloat(coder.decodeDouble(forKey: MKMapCamera.KEY_PITCH))
centerCoordinate.latitude = coder.decodeDouble(forKey: MKMapCamera.KEY_LATITUDE)
centerCoordinate.longitude = coder.decodeDouble(forKey: MKMapCamera.KEY_LONGITUDE)
}
}回答 1
Stack Overflow用户
发布于 2019-04-08 21:16:06
也有同样的问题。我的变通方法是在我的视图控制器的viewDidAppear中设置mapView.camera。
let mapCameraKey = "MapCameraKey"
var restoredCamera: MKMapCamera?
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if let restoredCamera = restoredCamera {
mapView.camera = restoredCamera
}
}
override func encodeRestorableState(with coder: NSCoder) {
super.encodeRestorableState(with: coder)
coder.encode(mapView.camera, forKey: mapCameraKey)
}
override func decodeRestorableState(with coder: NSCoder) {
super.decodeRestorableState(with: coder)
restoredCamera = coder.decodeObject(forKey: mapCameraKey) as? MKMapCamera
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/53289090
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