Best way to move the region of a SwiftUI Map

Question

Created Jun ’20

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I'm trying to have the region of a SwiftUI Map show a specific train. The compiler complains that the train property (see sample code below) is not available when the region property is being initialized. My solution to this is to set the location to the centre of the city, then set it to the train's location when the view appears.

Code Block swiftstruct MapView: View {
    @Binding var train: Train
    @State var region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: CLLocationDegrees(/* coordinate	presented as a Double literal */), longitude: CLLocationDegrees(/* coordinate	presented as a Double literal */)), latitudinalMeters: CLLocationDistance(1000), longitudinalMeters: CLLocationDistance(1000))
    
    var body: some View {
        Map(coordinateRegion: $region, interactionModes: .zoom, annotationItems: [train], annotationContent: { (train) in
            return MapMarker.init(coordinate: CLLocationCoordinate2D(latitude: CLLocationDegrees(train.position!.latitude), longitude: CLLocationDegrees(train.position!.longitude)))
        })
        .edgesIgnoringSafeArea(.bottom)
        .navigationBarTitle("Train #\(train.runNumber)")
        .onAppear {
            region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: CLLocationDegrees(train.position!.latitude), longitude: CLLocationDegrees(train.position!.longitude)), span: MKCoordinateSpan(latitudeDelta: CLLocationDegrees(1000), longitudeDelta: CLLocationDegrees(1000)))
        }
    }
}

Answered by Frameworks Engineer in 616048022

Hi thafner,

Apologies, linked the wrong post before. The correct link for the post that gives example code for how to programmatically change the region of the Map can be found here.

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Answer 1

Frameworks Engineer OP

Apple

Jun ’20

Hello thafner,

Guidance for programmatically changing the region of the Map was given in a previous post and can be seen here

Let us know if you have any further question!

1

Answer 2

Frameworks Engineer OP

Apple

Jun ’20

Accepted Answer

Hi thafner,

Apologies, linked the wrong post before. The correct link for the post that gives example code for how to programmatically change the region of the Map can be found here.

0