[英]How to set @EnvironmentObject in an existing Storyboard based project?
[英]How to set value to EnvironmentObject from class?
我想从 Delegate 类为 EnvironmentObject 设置值。
struct AppleMapView: UIViewRepresentable {
@EnvironmentObject var mapViewViewModel: MapViewViewModel
let mapViewDelegate = MapViewDelegate()
class MapViewDelegate: NSObject, MKMapViewDelegate {
func mapView(_ mapView: MKMapView, didChange mode: MKUserTrackingMode, animated: Bool) {
// This is where I want to set value to EnvObj
**mapViewViewModel.mode = mode**
}
}
}
这就是我想要做的。
我的代码给出错误
Instance member 'mapViewViewModel' of type 'AppleMapView' cannot be used on instance of nested type 'AppleMapView.MapViewDelegate'
所以,我尝试引用委托类:
MapViewDelegate(vm: mapViewViewModel)
这没有编译错误,但是当我运行代码时它出错了
A View.environmentObject(_:) for MapViewViewModel may be missing as an ancestor of this view.: file /BuildRoot/Library/Caches/com.apple.xbs/Sources/Monoceros_Sim/Monoceros-39.4.3/Core/EnvironmentObject.swift, line 55 ```
两者都不起作用。 我该如何修复我的代码?
它以不同的方式工作,它需要让你的MapViewDelegate
作为MapViewDelegate
协调AppleMapView
,如下所示
struct AppleMapView: UIViewRepresentable {
@EnvironmentObject var mapViewViewModel: MapViewViewModel
func makeUIView(context: Context) -> MKMapView {
let mapView = MKMapView()
mapView.delegate = context.coordinator // << your delegate
return mapView
}
func makeCoordinator() -> MapViewDelegate {
MapViewDelegate(self) // << will be created for you
}
class MapViewDelegate: NSObject, MKMapViewDelegate {
var owner: AppleMapView
init(_ owner: AppleMapView) {
self.owner = owner
}
func mapView(_ mapView: MKMapView, didChange mode: MKUserTrackingMode, animated: Bool) {
owner.mapViewViewModel.mode = mode // << now you have access to owner props
}
}
}
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