App Store Product Page Header & Creative Assets

import Foundation

// MARK: - App Store Connect API: Upload Creative Asset to Asset Library
// Requires: App Store Connect API key with Apps + App Store access
// Replace placeholders with your real values from App Store Connect

let apiKeyId      = "YOUR_API_KEY_ID"
let issuerId      = "YOUR_ISSUER_ID"
let privateKeyPem = """  // paste your .p8 content here (no header/footer lines)
    MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg...
"""

// MARK: - JWT Token Builder (ES256)
import CryptoKit

struct AppStoreConnectJWT {
    static func token(keyId: String, issuerId: String, pemKey: String) throws -> String {
        let header = #"{"alg":"ES256","kid":"\#(keyId)","typ":"JWT"}"#
        let now    = Int(Date().timeIntervalSince1970)
        let payload = """
        {"iss":"\(issuerId)","iat":\(now),"exp":\(now + 1200),\
        "aud":"appstoreconnect-v1"}
        """
        func b64(_ s: String) -> String {
            Data(s.utf8).base64EncodedString()
                .replacingOccurrences(of: "=", with: "")
                .replacingOccurrences(of: "+", with: "-")
                .replacingOccurrences(of: "/", with: "_")
        }
        let unsigned = "\(b64(header)).\(b64(payload))"
        let keyData  = Data(base64Encoded: pemKey
            .components(separatedBy: .newlines)
            .filter { !$0.hasPrefix("---") }
            .joined()) ?? Data()
        let privateKey = try P256.Signing.PrivateKey(derRepresentation: keyData)
        let signature  = try privateKey.signature(for: Data(unsigned.utf8))
        let sigB64 = signature.derRepresentation
            .base64EncodedString()
            .replacingOccurrences(of: "=", with: "")
            .replacingOccurrences(of: "+", with: "-")
            .replacingOccurrences(of: "/", with: "_")
        return "\(unsigned).\(sigB64)"
    }
}

// MARK: - Upload creative asset metadata (Step 1 of 2: reserve the asset)
async func reserveCreativeAsset(appId: String, jwt: String) async throws -> String {
    let url = URL(string: "https://api.appstoreconnect.apple.com/v1/appStoreVersionLocalizations")!
    // In practice you POST to the Asset Library endpoint:
    // POST /v1/apps/{appId}/creativeAssets  (replace with GA endpoint name)
    var req = URLRequest(url: url)
    req.httpMethod = "POST"
    req.setValue("Bearer \(jwt)", forHTTPHeaderField: "Authorization")
    req.setValue("application/json", forHTTPHeaderField: "Content-Type")
    let body: [String: Any] = [
        "data": [
            "type": "creativeAssets",
            "attributes": [
                "fileName": "summer_header.png",
                "fileSize": 512_000,
                "assetType": "PRODUCT_PAGE_HEADER"
            ],
            "relationships": [
                "app": ["data": ["type": "apps", "id": appId]]
            ]
        ]
    ]
    req.httpBody = try JSONSerialization.data(withJSONObject: body)
    let (data, _) = try await URLSession.shared.data(for: req)
    let json = try JSONSerialization.jsonObject(with: data) as? [String: Any]
    let assetId = (json?["data"] as? [String: Any])?["id"] as? String ?? ""
    print("Reserved creative asset ID:", assetId)
    return assetId
}

// MARK: - Entry point
Task {
    do {
        let jwt     = try AppStoreConnectJWT.token(keyId: apiKeyId,
                                                    issuerId: issuerId,
                                                    pemKey: privateKeyPem)
        let assetId = try await reserveCreativeAsset(appId: "YOUR_APP_ID", jwt: jwt)
        print("Next: upload binary to the upload URL, then PATCH to commit asset:", assetId)
    } catch {
        print("Error:", error)
    }
}