iOS 11 Swift 4下Apple Music Kit用户令牌获取失败问题求助

Hey there, let's work through that user token problem you're hitting with the "Adding-content-to-Apple-Music" sample project. Since you've already confirmed your developer token is valid and all authorization statuses show as authorized, here are some focused steps to get to the bottom of this:

1. Double-Check Your User Token Request Implementation #

• Make sure when calling SKCloudServiceController.requestUserToken(forDeveloperToken:), your developer token doesn't have extra whitespace or line breaks—copy-pasting can sometimes sneak in invisible characters that break validation.
• Verify you're handling the callback correctly, and that you're initiating the request after confirming the authorization status. Here's a quick sanity check snippet to align with:

  let cloudController = SKCloudServiceController()
  guard SKCloudServiceController.authorizationStatus() == .authorized else {
      print("Cloud service not authorized—handle this first!")
      return
  }
  
  cloudController.requestUserToken(forDeveloperToken: yourValidDeveloperToken) { userToken, error in
      if let error = error {
          // Print full error details, not just the localized message
          print("User token request failed: \(error)")
          return
      }
      
      guard let token = userToken else {
          print("User token came back nil")
          return
      }
      
      // Proceed with your Music Kit operations using the token
  }
  

• Ensure you're calling this method on the main thread—SKCloudServiceController methods are designed to be used there, and off-thread calls can cause unexpected behavior.

2. Re-Validate Your Developer Token #

Even though you believe it's correct, it's worth a quick double-check:

• Confirm your token hasn't expired—Apple's developer tokens are valid for 6 months, so if you generated it a while back, it might be time to create a new one.
• Verify you used the correct Team ID, Key ID, and matching private key when generating the token, and that you signed it with the ES256 algorithm (this is non-negotiable for Music Kit tokens).

3. Audit Your Project Configuration #

• Make sure your Xcode project has the MusicKit capability enabled (go to your project's Signing & Capabilities tab, click "+ Capability" and add MusicKit if it's missing).
• Check your Info.plist for the NSAppleMusicUsageDescription key—even though authorization succeeded, a missing or invalid description can cause silent failures in subsequent requests.
• Confirm your test device's Apple ID has an active Apple Music subscription. The "Music Catalog Subscription Eligible" status means the user can subscribe, but an active subscription is required for certain token-dependent operations.

4. Rule Out Network & Environment Glitches #

• Disable any VPN or proxy on your test device—these can block communication with Apple's Music service servers.
• Restart both Xcode and your test device to clear any cached authorization states or temporary network issues.
• Ensure your network doesn't have firewalls blocking access to Apple's Music-related domains (like music.apple.com or api.music.apple.com).

5. Dig Into Detailed Error Logs #

The key to pinpointing the issue might be in the full error object, not just the localized message. Modify your callback to print the entire error:

print("Full error breakdown: \(error!)")

This will give you specific error codes from the SKErrorDomain (like .permissionDenied, .notFound, or .serviceUnavailable) that can tell you exactly what's going wrong.

内容的提问来源于stack exchange，提问作者virajd