A code snippet for detecting the TestFlight environment for a macOS app at runtime

Bundle+TestFlight.swift

import Foundation
import Security

extension Bundle {
    
    /// Returns whether the bundle was signed for TestFlight beta distribution by checking
    /// the existence of a specific extension (marker OID) on the code signing certificate.
    ///
    /// This routine is inspired by the source code from ProcInfo, the underlying library
    /// of the WhatsYourSign code signature checking tool developed by Objective-See. Initially,
    /// it checked the common name but was changed to an extension check to make it more
    /// future-proof.
    ///
    /// For more information, see the following references:
    /// - https://github.com/objective-see/ProcInfo/blob/master/procInfo/Signing.m#L184-L247
    /// - https://gist.github.com/lukaskubanek/cbfcab29c0c93e0e9e0a16ab09586996#gistcomment-3993808
    internal var isTestFlight: Bool {
        var status = noErr

        var code: SecStaticCode?
        status = SecStaticCodeCreateWithPath(bundleURL as CFURL, [], &code)

        guard status == noErr, let code = code else { return false }

        var requirement: SecRequirement?
        status = SecRequirementCreateWithString(
            "anchor apple generic and certificate leaf[field.1.2.840.113635.100.6.1.25.1]" as CFString,
            [], // default
            &requirement
        )

        guard status == noErr, let requirement = requirement else { return false }

        status = SecStaticCodeCheckValidity(
            code,
            [], // default
            requirement
        )

        return status == errSecSuccess
    }
    
}