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

Bundle+TestFlight.swift

/// MIT License
///
/// Copyright (c) 2021 Lukas Kubanek, Structured Path GmbH
///
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to deal
/// in the Software without restriction, including without limitation the rights
/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
/// copies of the Software, and to permit persons to whom the Software is
/// furnished to do so, subject to the following conditions:
///
/// The above copyright notice and this permission notice shall be included in all
/// copies or substantial portions of the Software.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
/// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
/// SOFTWARE.

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
    }
    
}

@jaanus: I’m glad this snipped helped you. To be honest, I haven’t checked whether the certificate-based method works on iOS as I currently don’t have any iOS app on TestFlight. If you happen to have one (I guess you’re using it for Tact, right?), you can test it for yourself and report back in this thread. Best luck with your project!

Yep, that’s the project where I use it. I’ll some time try it out with iOS on TestFlight and report back.

Verdict about iOS: cannot use the signature check, because the needed Security framework API-s are available only on macOS and not on iOS.

So as far as I know, the best way to do this across macOS and iOS is what I shared above. On macOS, do the signature check from the original post. On iOS, check the receipt file name.

@jaanus: Thanks for sharing your findings!

Months later, I wanted to add that I've been using this trick on my public macOS beta for a while, to restrict in-app features. It has worked like a charm since.

@lukaskubanek Thanks for figuring this out. Very handy to have while publicly testing new features!

I feel like sharing what I ended up doing, as it might help other readers:

https://github.com/passepartoutvpn/passepartout-apple/blob/master/PassepartoutLibrary/Sources/PassepartoutCore/Reusable/SandboxChecker.swift

Beyond being a multiplatform check, I made this observable because Xcode has been complaining about SecStaticCodeCheckValidity for a while, as it is a potentially slow call.

Also notice that the Mac condition appears first, because #if os(iOS) is also met on Catalyst and would take over.

@keeshux Thanks, but it's a shame it's GPL as I don't particularly want to open source my whole application just to check if I'm running on Testflight or not. I think for most people the one in this thread is a safer bet.