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SwiftUI - View annotations

Add/remove view annotation on tap.

ViewAnnotationsExample.swift
import SwiftUI
import Turf
@_spi(Experimental) import MapboxMaps
@available(iOS 14.0, *)
struct ViewAnnotationsExample: View {
@State private var taps: [Tap] = []
@State private var allowOverlap: Bool = false
@State private var selected = false
@State private var etaAnnotationAnchor = ViewAnnotationAnchor.center
@State private var overlayHeight: CGFloat = 0
var body: some View {
Map(initialViewport: .camera(center: .helsinki, zoom: 5)) {
// A single view annotation, tap on it to change selected state.
MapViewAnnotation(coordinate: .helsinki) {
Text("🏠")
.frame(width: 22, height: 22)
.scaleEffect(selected ? 1.8 : 1)
.padding(selected ? 20 : 10)
.background(
Circle().fill(selected ? .red : .blue))
.animation(.spring(), value: selected)
.onTapGesture {
selected.toggle()
}
}
.allowOverlap(allowOverlap)
.selected(selected)
// Dynamic view annotations, appeared on tap.
// The anchor can point to bottom, top, left, or right direction.
ForEvery(taps) { tap in
MapViewAnnotation(coordinate: tap.coordinate) {
ViewAnnotationContent(tap: tap) {
taps.removeAll(where: { $0.id == tap.id })
}
}
.allowOverlap(allowOverlap)
// Allow bottom, top, left, right positions of anchor.
.variableAnchors(
[ViewAnnotationAnchor.bottom, .top, .left, .right].map { .init(anchor: $0) }
)
.onAnchorChanged { config in
guard let idx = taps.firstIndex(where: { $0.id == tap.id }) else { return }
taps[idx].selectedAnchor = config
}
}
// A Dynamic View Annotation annotation, that is attached to the Polyline annotation.
let routeLayer = "route"
let routeFeature = "route-feature"
MapViewAnnotation(layerId: routeLayer, featureId: routeFeature) {
Text("1h 30m")
.padding(3)
.callout(
anchor: etaAnnotationAnchor,
color: Color(UIColor.systemBackground),
tailSize: 5.0)
}
.allowOverlap(allowOverlap)
.variableAnchors(.all) // Allow all directions for anchor
.onAnchorChanged { self.etaAnnotationAnchor = $0.anchor }
.selected(true)
// Route polyline
PolylineAnnotationGroup {
PolylineAnnotation(id: routeFeature, lineCoordinates: routeCoordinates)
.lineColor("#57A9FB")
.lineBorderColor("#327AC2")
.lineWidth(10)
.lineBorderWidth(2)
}
.layerId(routeLayer) // Specify id for underlying line layer.
.lineCap(.round)
.slot("middle") // Display above roads and below 3D buildings and labels (for Standard Style).
}
.presentsWithTransaction(true) // Synchronize Metal and CALayer for better VA performance.
.onMapTapGesture { context in
taps.append(Tap(coordinate: context.coordinate))
}
// Add bottom padding for the bottom config panel, View Annotations won't appear there.
.additionalSafeAreaInsets(.bottom, overlayHeight)
.ignoresSafeArea(edges: [.leading, .trailing, .bottom])
.safeOverlay(alignment: .bottom) {
VStack(alignment: .leading) {
Text("Tap to add annotations")
Toggle("Allow overlap", isOn: $allowOverlap)
}
.padding(.horizontal, 10)
.padding(.vertical, 6)
.floating(RoundedRectangle(cornerRadius: 10))
.onChangeOfSize { size in
overlayHeight = size.height
}
}
}
}
@available(iOS 13.0, *)
private struct Tap: Identifiable {
var id = UUID()
var coordinate: CLLocationCoordinate2D
var color: Color = .random
var selectedAnchor: ViewAnnotationAnchorConfig?
}
@available(iOS 14.0, *)
private struct ViewAnnotationContent: View {
var tap: Tap
var onRemove: () -> Void
@State var appeared = false
var body: some View {
let latlon = String(format: "%.2f, %.2f", tap.coordinate.latitude, tap.coordinate.longitude)
HStack(alignment: .firstTextBaseline) {
Text("(\(latlon))")
.font(.safeMonospaced)
Image(systemName: "clear.fill")
.onTapGesture(perform: onRemove)
}
.padding(5)
.foregroundColor(.white)
// Wrap annotation view into callout shape.
.callout(anchor: tap.selectedAnchor?.anchor ?? .center, color: tap.color)
.opacity(appeared ? 1 : 0)
.scaleEffect(appeared ? 1 : 0.2)
.animation(.spring(), value: appeared)
.onAppear {
appeared = true
}
.onDisappear {
appeared = false
}
}
private func tail() -> some View {
tap.color.frame(width: 6, height: 6)
}
}
private let routeCoordinates: [CLLocationCoordinate2D] = [
.init(latitude: 61.493343399275375, longitude: 21.79401104323395),
.init(latitude: 61.369485877583685, longitude: 21.6497937188623),
.init(latitude: 61.20121331932606, longitude: 21.723373986398713),
.init(latitude: 61.15722935505474, longitude: 21.579156662028026),
.init(latitude: 61.1174491345069, longitude: 21.517349237298163),
.init(latitude: 61.03916342463762, longitude: 21.532065290804866),
.init(latitude: 60.922086661997184, longitude: 21.611531979743546),
.init(latitude: 60.82754056454698, longitude: 21.82049993954618),
.init(latitude: 60.662131116075585, longitude: 22.02063826724438),
.init(latitude: 60.543665503992116, longitude: 22.129538402396946),
.init(latitude: 60.461061119997595, longitude: 22.206061880634536),
.init(latitude: 60.4538050749446, longitude: 22.270812516066485)
]
@available(iOS 14.0, *)
struct ViewAnnotationsExample_Previews: PreviewProvider {
static var previews: some View {
ViewAnnotationsExample()
}
}
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