[英]SwiftUI MapKit UIViewRepresentable Can't present Alert
I have a SwiftUI app where a couple of views are MapKit maps made with UIViewRepresentable.我有一个 SwiftUI 应用程序,其中有几个视图是使用 UIViewRepresentable 制作的 MapKit 地图。 I have custom annotations for the points of interest and use both the right and left callout buttons for further action.我有兴趣点的自定义注释,并使用左右标注按钮进行进一步操作。 On the right I simply want to display information about the waypoint.在右侧,我只想显示有关航点的信息。 On the left I want to raise an alert with a choice of further actions - for example, insert a new annotation point.在左侧,我想通过选择进一步的操作来发出警报 - 例如,插入一个新的注释点。 Before SwiftUI I just raised an alert and did both of the above.在 SwiftUI 之前,我只是提出了一个警报并执行了上述两项操作。 But from what I can tell, there is no self.present on the UIViewRepresentable versions.但据我所知, UIViewRepresentable 版本上没有 self.present 。 Hence I have not been able to present alerts.因此,我无法显示警报。
Just for an experiment - I attached SwiftUI alert code to the SwiftUI view that calls the MapView.仅用于实验 - 我将 SwiftUI 警报代码附加到调用 MapView 的 SwiftUI 视图。 Using Observable booleans I can indeed raise both those alerts.使用 Observable 布尔值,我确实可以同时发出这些警报。 That seems strange to me but maybe the code for alerts bound to global properties can be ANYWHERE.这对我来说似乎很奇怪,但也许绑定到全局属性的警报代码可以在任何地方。
My first attempt: (the struct is DetailMapView)我的第一次尝试:(结构是 DetailMapView)
func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
if control == view.leftCalloutAccessoryView {
guard let tappedLocationCoord = view.annotation?.coordinate else {return}
let tappedLocation = CLLocation(latitude: tappedLocationCoord.latitude, longitude: tappedLocationCoord.longitude)
let ac = UIAlertController(title: nil, message: nil, preferredStyle: .alert)
let deleteAction = UIAlertAction(title: "Delete Waypoint", style: .destructive) { (action) in
//some stuff
}
let insertAction = UIAlertAction(title: "Insert Waypoint After This", style: .default) { (action) in
//some stuff
}
let cancelAction = UIAlertAction(title: "Cancel", style: .default) { (action) in
//some stuff
}//cancelAction
ac.addAction(deleteAction)
ac.addAction(insertAction)
ac.addAction(cancelAction)
//tried adding self, referencing parent - always error saying
//the object does not have a .present
mapView.present(ac, animated: true)
} else if control == view.rightCalloutAccessoryView {
//more of the same
}
}//annotationView
I then removed the alert code and added:然后我删除了警报代码并添加了:
parent.userDefaultsManager.shouldShowAnnotationEditMenu.toggle()
And I changed the calling screen to:我将呼叫屏幕更改为:
@ObservedObject var userDefaultsManager: UserDefaultsManager
var aTrip: Trip?
var body: some View {
VStack {
Text(aTrip?.name ?? "Unknown Map Name")
.padding(.top, -50)
.padding(.bottom, -20)
DetailMapView(aTrip: aTrip, userDefaultsManager: userDefaultsManager)
.padding(.top, -20)
.alert(isPresented: $userDefaultsManager.shouldShowAddress) {
//Alert(title: Text("\(aTrip?.name ?? "No") Address"),
Alert(title: Text(self.userDefaultsManager.approximateAddress),
message: Text("This is the approximate street address."),
dismissButton: .default(Text("Got it!")))
}//.alert shouldShowAddress
Text("This is the view where the trip information will be displayed.")
.multilineTextAlignment(.center)
.alert(isPresented: $userDefaultsManager.shouldShowAnnotationEditMenu) {
Alert(title: Text("Edit Annotations"),
message: Text("Choose this to insert an Annotation."),
dismissButton: .default(Text("Got it!")))
}//.alert shouldShowAddress
}
}
I guess if this is safe I could make it work - but it seems more complicated that it should be.我想如果这是安全的,我可以让它工作 - 但它应该看起来更复杂。
This is the idea:这是想法:
Any guidance would be appreciated: Xcode Version 11.3.1 (11C504)任何指导将不胜感激:Xcode 版本 11.3.1 (11C504)
I spent an hour for this, I'm new to SwiftUI, and I jumped into it just to answer some easy questions.我为此花了一个小时,我是 SwiftUI 的新手,我跳进去只是为了回答一些简单的问题。
One way to do what you want is to use Bool
( @State
and @Binding
).做你想做的一种方法是使用Bool
( @State
和@Binding
)。
You also need to have a View
rather than directly use your UIViewRepresentable
in your SceneDelegate
.您还需要有一个View
而不是直接在UIViewRepresentable
中使用SceneDelegate
。 Because that is where you will chain your alert
.因为那是您链接alert
。
Like so:像这样:
struct MainView: View {
@State var text = ""
@State var showingAlert: Bool
var body: some View {
VStack {
MapView(showingAlert: self.$showingAlert)
.alert(isPresented: $showingAlert) { () -> Alert in
print("SHOWING ALERT BODY: --> \($showingAlert.wrappedValue)")
return Alert(title: Text("Important message"), message: Text("Go out and have a girlfriend!"), dismissButton: .default(Text("Got it!")))
}
}
}
}
and then your MapView
should go like this:然后你的MapView
应该是这样的:
struct MapView: UIViewRepresentable {
let landmarks = LandmarkAnnotation.requestMockData()
@Binding var showingAlert: Bool
func makeCoordinator() -> MapViewCoordinator {
MapViewCoordinator(mapView: self, showingAlert: self.$showingAlert)
}
/**
- Description - Replace the body with a make UIView(context:) method that creates and return an empty MKMapView
*/
func makeUIView(context: Context) -> MKMapView {
MKMapView(frame: .zero)
}
func updateUIView(_ view: MKMapView, context: Context){
//If you changing the Map Annotation then you have to remove old Annotations
//mapView.removeAnnotations(mapView.annotations)
view.delegate = context.coordinator
view.addAnnotations(landmarks)
}
}
struct MapView_Previews: PreviewProvider {
static var previews: some View {
MapView(showingAlert: Binding<Bool>.constant(true))
}
}
Finally, in your MapViewCoordinator
(I suppose you have this class, this is the one that implements the delegate methods of the MKMapViewDelegate
.).最后,在您的MapViewCoordinator
(我想您有这个类,这是实现MKMapViewDelegate
的委托方法的类。)。
/*
Coordinator for using UIKit inside SwiftUI.
*/
class MapViewCoordinator: NSObject, MKMapViewDelegate {
var mapViewController: MapView!
@Binding var showAlert: Bool
init(mapView: MapView, showingAlert: Binding<Bool>) {
self.mapViewController = mapView
self._showAlert = showingAlert
super.init()
}
func mapView(_ mapView: MKMapView, viewFor
annotation: MKAnnotation) -> MKAnnotationView?{
//Custom View for Annotation
let annotationView = MKAnnotationView(annotation: annotation, reuseIdentifier: "customView")
annotationView.canShowCallout = true
//Your custom image icon
annotationView.image = UIImage(named: "locationPin")
return annotationView
}
func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
print("calloutAccessoryControlTapped")
}
func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
print("didSelect")
self.showAlert = true
}
}
So as you can see, I just make use of the Bool flag.如您所见,我只是使用 Bool 标志。 Especially the @Binding
one.特别是@Binding
之一。
Yes, Glenn.是的,格伦。
This is actually the way I did it.这实际上是我做的方式。 I had used ObservedObjects
.我曾经使用过ObservedObjects
。 However I think your approach with @State
and @Binding
is better.但是我认为您使用@State
和@Binding
方法更好。 Also, I do not want to show the map conditionally - just want to show annotation connections.另外,我不想有条件地显示地图 - 只想显示注释连接。 For some reason I was not able to add a comment to your answer so replying here.出于某种原因,我无法在您的答案中添加评论,因此在此处回复。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.