我为喜欢飞机的女儿做了一个雷达APP，来发现天空中的飞机

final class LocationManager: CLLocationManager, CLLocationManagerDelegate {            static let shared = LocationManager()        private(set) var rotationAngleSubject = CurrentValueSubject<Double, Never>(0)        override private init() {        super.init()        requestWhenInUseAuthorization()        delegate = self        startUpdatingHeading()    }        func locationManager(_ manager: CLLocationManager, didUpdateHeading newHeading: CLHeading) {        rotationAngleSubject.send(-newHeading.magneticHeading)    }}

@State private var rotationAngle: Angle = .degrees(0)

var body: some View {    ZStack {        ForEach(0..<36) {            let angle = Angle.degrees(Double($0 * 10)) + rotationAngle            Rectangle()                .frame(width: $0 == 0 ? 16 : 8, height: $0 == 0 ? 3 : 2)                .foregroundColor($0 == 0 ? .red : .blue)                .rotationEffect(angle)                .offset(x: 120 * cos(CGFloat(angle.radians)), y: 120 * sin(CGFloat(angle.radians)))                .animation(.bouncy, value: rotationAngle)        }    }    .onReceive(LocationManager.shared.rotationAngleSubject) { angle in        rotationAngle = Angle.degrees(angle)    }}

https://opensky-network.org/api/states/all?lamin=51.0&lamax=52.0&lomin=-0.5&lomax=0.5

struct Flight: Decodable {

    let icao24: String     let callsign: String?    let origin_country: String?     let time_position: Int?    let last_contact: Int    let longitude: Double    let latitude: Double

    // ... 

    init(from decoder: Decoder) throws {        var container = try decoder.unkeyedContainer()        icao24 = try container.decode(String.self)        callsign = try? container.decode(String?.self)        origin_country = try container.decode(String.self)        time_position = try? container.decode(Int?.self)        last_contact = try container.decode(Int.self)        longitude = try container.decode(Double.self)        latitude = try container.decode(Double.self)

        // ...    }}

final class FlightAPI {        func fetchLocalFlightData(coordinate: CLLocationCoordinate2D) async throws -> [Flight] {                let lamin = String(format: "%.1f", coordinate.latitude - 0.25)        let lamax = String(format: "%.1f", coordinate.latitude + 0.25)        let lomin = String(format: "%.1f", coordinate.longitude - 0.5)        let lomax = String(format: "%.1f", coordinate.longitude + 0.5)

        let url = URL(string: "https://opensky-network.org/api/states/all?lamin=(lamin)&lamax=(lamax)&lomin=(lomin)&lomax=(lomax)")!        let data = try await URLSession.shared.data(from: url).0        return try JSONDecoder().decode([Flight].self, from: data)    }}

@State private var coordinates: CLLocationCoordinate2D?@State private var flights: [Flight] = []

private var airplanes: some View {    ForEach(flights, id: .icao24) { flight in        let latDiff = coordinate.latitude - (flight.latitude ?? 0)        let lngDiff = coordinate.longitude - (flight.longitude ?? 0)        Image(systemName: "airplane")            .resizable()            .frame(width: 20, height: 20)            .rotationEffect(.degrees(flight.true_track ?? 0))            .foregroundColor(.red)            .offset(x: 250 * latDiff, y: 250 * lngDiff)    }}

@State private var cameraPosition: MapCameraPosition = .camera(MapCamera(        centerCoordinate: CLLocationCoordinate2D(latitude: 51.0, longitude: 0.0),        distance: 100_000,        heading: 0))

var body: some View {    ZStack {        Map(position: $cameraPosition) { }         airplanes        compass    }}

import MapKitimport SwiftUI

struct FlightMapView: View {        @Binding var cameraPosition: MapCameraPosition        let flights: [Flight]

    var body: some View {        Map(position: $cameraPosition) {            planeMapAnnotations        }        .mapStyle(.imagery)        .allowsHitTesting(false)    }}

@State private var rotationAngle: Angle = .degrees(0)

private var planeMapAnnotations: some MapContent {    ForEach(flights, id: .icao24) { flight in        Annotation(flight.icao24, coordinate: flight.coordinate) {            let rotation = rotationAngle.degrees + flight.true_track            let scale = min(2, max(log10(height + 1), 0.5))            Image(systemName: "airplane")                .rotationEffect(.degrees(rotation))                .scaleEffect(scale)            }        }        .tint(.white)    }}

min(2, max(4.7 - log10(flight.geo_altitude + 1), 0.7))

Scale:  1.0835408863965839Scale:  0.8330645861650874Scale:  1.095791123396205Scale:  1.1077242935783653Scale:  2.0Scale:  1.4864702267977097Scale:  0.7

private func fetchFlights(at coordinate: CLLocationCoordinate2D, retries: Int = 3) async {    do {        try await api.fetchLocalFlightData(coordinate: coordinate)

    } catch {        if retries > 0 {            try await fetchFlights(at: coordinate, retries: retries - 1)        }    }}

struct FlightMapView: View {

    var body: some View {        Map(position: $cameraPosition) {            planeMapAnnotations            MapPolygon(overlay(coordinate: coordinate))        }        .mapStyle(.imagery)        .allowsHitTesting(false)    }

    // ...        private func rectangle(around coordinate: CLLocationCoordinate2D) -> [CLLocationCoordinate2D] {        [            CLLocationCoordinate2D(latitude: coordinate.latitude - 1, longitude: coordinate.longitude - 1),            CLLocationCoordinate2D(latitude: coordinate.latitude - 1, longitude: coordinate.longitude + 1),            CLLocationCoordinate2D(latitude: coordinate.latitude + 1, longitude: coordinate.longitude + 1),            CLLocationCoordinate2D(latitude: coordinate.latitude + 1, longitude: coordinate.longitude - 1)        ]    }        private func overlay(coordinate: CLLocationCoordinate2D) -> MKPolygon {        let rectangle = rectangle(around: coordinate)        return MKPolygon(coordinates: rectangle, count: rectangle.count)    }}

private var radarLine: some View {    Circle()        .fill(            AngularGradient(                gradient: Gradient(colors: [                    Color.black, Color.black, Color.black, Color.black,                    Color.black.opacity(0.8), Color.black.opacity(0.6),                    Color.black.opacity(0.4), Color.black.opacity(0.2),                    Color.clear, Color.clear, Color.clear, Color.clear,                    Color.clear, Color.clear, Color.clear, Color.clear,                    Color.clear, Color.clear, Color.clear, Color.green]),                center: .center,                startAngle: .degrees(rotationDegree),                endAngle: .degrees(rotationDegree + 360)            )        )        .rotationEffect(Angle(degrees: rotationDegree))        .animation(.linear(duration: 6).repeatForever(autoreverses: false), value: rotationDegree)}

#include <metal_stdlib>using namespace metal;

[[ stitchable ]] half4 crtScreen(    float2 position,    half4 color,    float time) {        if (all(abs(color.rgb - half3(0.0, 0.0, 0.0)) < half3(0.01, 0.01, 0.01))) {        return color;    }        const half scanlineIntensity = 0.2;    const half scanlineFrequency = 400.0;    half scanlineValue = sin((position.y + time * 10.0) * scanlineFrequency * 3.14159h) * scanlineIntensity;    return half4(color.rgb - scanlineValue, color.a);}

extension View {        func crtScreenEffect(startTime: Date) -> some View {        modifier(CRTScreen(startTime: startTime))    }}

struct CRTScreen: ViewModifier {        let startTime: Date        func body(content: Content) -> some View {        content            .colorEffect(                ShaderLibrary.crtScreen(                    .float(startTime.timeIntervalSinceNow)                )            )    }}

private func fetchFlights(coordinate: Coordinate, retries: Int = 2) async {    do {        let flights = try await api.fetchLocalFlightData(coordinate: coordinate)        await MainActor.run {            self.flights = flights            AudioServicesPlaySystemSound(1052)            hapticTrigger.toggle()        }

    // ...

}

.sensoryFeedback(.levelChange, trigger: hapticTrigger)

@AppStorage("silent") var silentMode: Bool = false@AppStorage("showMap") var showMap: Bool = false@AppStorage("userColor") var userColor: Color = .green

private func toggleableIcon(state: Bool, iconTrue: String, iconFalse: String) -> some View {        Image(systemName: state ? iconTrue : iconFalse)            .contentTransition(.symbolEffect(.replace))    // ...}

// @State properties ...

var body: some View {    ZStack {        if let coordinate = locationManager.coordinateSubject.value {            FlightMapView(                cameraPosition: $cameraPosition,                flights: flights,                rotationAngle: rotationAngle,                coordinate: coordinate            )        }            TimelineView(.animation) { context in            RadarView()                .crtScreenEffect()                .negativeHighlight()        }            ControlsView(errorMessage: errorMessage)    }

    // onRecieve modifiers ...}