Xcode 9.3+iOS 11环境Swift项目添加plist临时例外后仍HTTP加载失败

Hey there, let's break down this SSL trust error you're facing with your Swift app on Xcode 9.3 and iOS 11. That HTTP load failed (error code: -1202 [3:-9843]) message tells us the system is rejecting the server's SSL certificate, even after you added ATS exceptions to your plist. Let's walk through the most common fixes:

1. Double-Check Your ATS Plist Configuration #

First, make sure your NSAppTransportSecurity settings are correctly formatted—small typos here are super common. If you're targeting a specific domain (not disabling ATS entirely), your plist should look like this:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSExceptionDomains</key>
    <dict>
        <key>your-target-domain.com</key>
        <dict>
            <!-- Include subdomains if needed -->
            <key>NSIncludesSubdomains</key>
            <true/>
            <!-- Allow insecure HTTP loads (if your server uses HTTP) -->
            <key>NSTemporaryExceptionAllowsInsecureHTTPLoads</key>
            <true/>
            <!-- Specify minimum TLS version if your server uses an older one (iOS 11 defaults to TLS 1.2) -->
            <key>NSTemporaryExceptionMinimumTLSVersion</key>
            <string>TLSv1.0</string>
        </dict>
    </dict>
</dict>

• Double-check that the domain matches exactly (no extra slashes or typos).
• If you used NSAllowsArbitraryLoads = YES, note that this overrides per-domain exceptions—so if you need specific rules, stick to NSExceptionDomains.

2. Verify SSL Certificate Trust (For Self-Signed Certificates) #

If you're using a self-signed certificate for testing:

• Install the certificate on your iOS 11 device (via email, Safari download, or configuration profile).
• Critical step for iOS 11+: Go to Settings > General > About > Certificate Trust Settings and enable full trust for your installed certificate. iOS 11 introduced this extra step to prevent untrusted certificates from being used by default.

3. Check the Server's SSL Certificate Chain #

Sometimes the error happens because the server's certificate chain is incomplete (missing intermediate certificates). To verify this:

• Open Terminal and run:

  openssl s_client -connect your-target-domain.com:443
  

• Look for the line verify return:1—if you see verify return:0, the certificate chain is broken, and you'll need to fix this on the server side by including all required intermediate certificates.

4. Temporary Test-Only Workaround (Never Use in Production!) #

If you need to bypass SSL validation strictly for testing purposes (e.g., local development), you can implement a URLSession delegate method to trust the server's certificate. Again, this is unsafe for production—only use this to confirm the issue is certificate-related:

extension YourViewController: URLSessionDelegate {
    func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        guard challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust else {
            completionHandler(.performDefaultHandling, nil)
            return
        }
        
        if let serverTrust = challenge.protectionSpace.serverTrust {
            let credential = URLCredential(trust: serverTrust)
            completionHandler(.useCredential, credential)
        } else {
            completionHandler(.performDefaultHandling, nil)
        }
    }
}

Make sure you assign this delegate to your URLSession instance when creating it.

Start with the first two steps—ATS misconfiguration and missing certificate trust are the most likely culprits here. If those don't work, check the certificate chain on your server.

内容的提问来源于stack exchange，提问作者Vaisakh Mohan