swift 10 lines · 1 tab

Client certificate pinning considerations for mobile apps

Kai Nakamura Apr 2026

1 tab

final class PinnedSessionDelegate: NSObject, URLSessionDelegate {
    func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
        guard let serverTrust = challenge.protectionSpace.serverTrust else {
            completionHandler(.cancelAuthenticationChallenge, nil)
            return
        }

        completionHandler(.useCredential, URLCredential(trust: serverTrust))
    }
}

1 file · swift Explain with highlit

Certificate pinning is useful in high-risk mobile scenarios, but it has real operational cost. I use it selectively, plan backup pins, and make sure the team can rotate infrastructure without bricking clients. Security controls that ignore operational reality eventually get ripped out.

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