本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

將適用於 iOS 的 Tangram ES 與 Amazon Location Service 搭配使用

Tangram ES 是 C++ 程式庫，用於使用 OpenGL ES 從向量資料轉譯 2D 和 3D 映射。這是 Tangram 的原生複本。

使用來自 的映射時，為搭配 Tilezen 結構描述使用而建置的 Tangram 樣式在很大程度上與 Amazon Location 相容HERE。其中包含：

本指南說明如何使用名為 Cinnabar 的 Tangram 樣式，將適用於 iOS 的 Tangram ES 與 Amazon Location 整合。此範例可作為 Amazon Location Service 範例儲存庫的一部分GitHub。

雖然其他 Tangram 樣式最好搭配編碼地形資訊的光柵圖磚，但 Amazon Location 尚不支援此功能。

建置應用程式：初始化

若要初始化應用程式：

建置應用程式：新增相依性

若要新增相依性，您可以使用相依性管理員，例如CocoaPods：

建置應用程式：組態

將下列金鑰和值新增至 Info.plist，以設定應用程式並停用遙測：

建置應用程式： ContentView 配置

若要轉譯映射，請編輯 ContentView.swift：

這也會設定地圖的初始中心點。

import SwiftUI
import TangramMap
 
struct ContentView: View {
    var body: some View {
        MapView()
            .cameraPosition(TGCameraPosition(
                                center: CLLocationCoordinate2DMake(49.2819, -123.1187),
                                zoom: 10,
                                bearing: 0,
                                pitch: 0))
            .edgesIgnoringSafeArea(.all)
            .overlay(
                Text("© 2020 HERE")
                    .disabled(true)
                    .font(.system(size: 12, weight: .light, design: .default))
                    .foregroundColor(.black)
                    .background(Color.init(Color.RGBColorSpace.sRGB, white: 0.5, opacity: 0.5))
                    .cornerRadius(1),
                alignment: .bottomTrailing)
    }
}
 
struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

建置應用程式：請求轉換

建立名為 的新 Swift 檔案，AWSSignatureV4URLHandler.swift其中包含下列類別定義，以攔截 AWS 請求並使用 Signature 第 4 版簽署請求。這將在 Tangram 中註冊為URL處理常式MapView。

import AWSCore
import TangramMap
 
class AWSSignatureV4URLHandler: TGDefaultURLHandler {
    private let region: AWSRegionType
    private let identityPoolId: String
    private let credentialsProvider: AWSCredentialsProvider
 
    init(region: AWSRegionType, identityPoolId: String) {
        self.region = region
        self.identityPoolId = identityPoolId
        self.credentialsProvider = AWSCognitoCredentialsProvider(regionType: region, identityPoolId: identityPoolId)
        super.init()
    }
 
    override func downloadRequestAsync(_ url: URL, completionHandler: @escaping TGDownloadCompletionHandler) -> UInt {
        if url.host?.contains("amazonaws.com") != true {
            // not an AWS URL
            return super.downloadRequestAsync(url, completionHandler: completionHandler)
        }
 
        // URL-encode spaces, etc.
        let keyPath = String(url.path.dropFirst())
        guard let keyPathSafe = keyPath.addingPercentEncoding(withAllowedCharacters: .urlPathAllowed) else {
            print("Invalid characters in path '\(keyPath)'; unsafe to sign")
            return super.downloadRequestAsync(url, completionHandler: completionHandler)
        }
 
        // sign the URL
        let endpoint = AWSEndpoint(region: region, serviceName: "geo", url: url)
        let requestHeaders: [String: String] = ["host": endpoint!.hostName]
        let task = AWSSignatureV4Signer
            .generateQueryStringForSignatureV4(
                withCredentialProvider: credentialsProvider,
                httpMethod: .GET,
                expireDuration: 60,
                endpoint: endpoint!,
                keyPath: keyPathSafe,
                requestHeaders: requestHeaders,
                requestParameters: .none,
                signBody: true)
        task.waitUntilFinished()
 
        if let error = task.error as NSError? {
            print("Error occurred: \(error)")
        }
 
        if let result = task.result {
            // have Tangram fetch the signed URL
            return super.downloadRequestAsync(result as URL, completionHandler: completionHandler)
        }
 
        // fall back to an unsigned URL
        return super.downloadRequestAsync(url, completionHandler: completionHandler)
    }
}

建置應用程式：地圖檢視

地圖檢視會負責初始化 執行個體AWSSignatureV4Delegate並設定基礎 MGLMapView，這會擷取資源並呈現地圖。它也會處理將屬性字串從樣式描述符的來源傳播回 ContentView。

建立名為 的新 Swift 檔案，MapView.swift其中包含下列struct定義：

import AWSCore
import TangramMap
import SwiftUI
 
struct MapView: UIViewRepresentable {
    private let mapView: TGMapView
 
    init() {
        let regionName = Bundle.main.object(forInfoDictionaryKey: "AWSRegion") as! String
        let identityPoolId = Bundle.main.object(forInfoDictionaryKey: "IdentityPoolId") as! String
        let mapName = Bundle.main.object(forInfoDictionaryKey: "MapName") as! String
        let sceneURL = URL(string: Bundle.main.object(forInfoDictionaryKey: "SceneURL") as! String)!
 
        let region = (regionName as NSString).aws_regionTypeValue()
 
        // rewrite tile URLs to point at AWS resources
        let sceneUpdates = [
            TGSceneUpdate(path: "sources.mapzen.url",
                          value: "https://maps.geo.\(regionName).amazonaws.com/maps/v0/maps/\(mapName)/tiles/{z}/{x}/{y}")]
 
        // instantiate a TGURLHandler that will sign AWS requests
        let urlHandler = AWSSignatureV4URLHandler(region: region, identityPoolId: identityPoolId)
 
        // instantiate the map view and attach the URL handler
        mapView = TGMapView(frame: .zero, urlHandler: urlHandler)
 
        // load the map style and apply scene updates (properties modified at runtime)
        mapView.loadScene(from: sceneURL, with: sceneUpdates)
    }
 
    func cameraPosition(_ cameraPosition: TGCameraPosition) -> MapView {
        mapView.cameraPosition = cameraPosition
 
        return self
    }
 
    // MARK: - UIViewRepresentable protocol
 
    func makeUIView(context: Context) -> TGMapView {
        return mapView
    }
 
    func updateUIView(_ uiView: TGMapView, context: Context) {
    }
}

執行此應用程式會以您選擇的樣式顯示全螢幕地圖。此範例可作為 Amazon Location Service 範例儲存庫的一部分GitHub。