Detect if a process runs under Rosetta 2 on Apple Silicon M1 or native. Works for macOS and iOS.

Architecture.swift

@objc(PSTArchitecture) class Architecture: NSObject {
    /// Check if process runs under Rosetta 2.
    ///
    /// Use to disable tests that use WebKit when running on Apple Silicon
    /// FB8920323: Crash in WebKit memory allocator on Apple Silicon when  iOS below 14
    /// Crash is in JavaScriptCore: bmalloc::HeapConstants::HeapConstants(std::__1::lock_guard<bmalloc::Mutex> const&)
    @objc class var isRosettaEmulated: Bool {
        // Issue is specific to Simulator, not real devices
        #if targetEnvironment(simulator)
        return processIsTranslated() == EMULATED_EXECUTION
        #else
        return false
        #endif
    }
}

let NATIVE_EXECUTION = Int32(0)
let EMULATED_EXECUTION = Int32(1)
let UNKNOWN_EXECUTION = -Int32(1)

/// Test if the process runs natively or under Rosetta
/// https://developer.apple.com/forums/thread/652667?answerId=618217022&page=1#622923022
private func processIsTranslated() -> Int32 {
    let key = "sysctl.proc_translated"
    var ret = Int32(0)
    var size: Int = 0
    sysctlbyname(key, nil, &size, nil, 0)
    let result = sysctlbyname(key, &ret, &size, nil, 0)
    if result == -1 {
        if errno == ENOENT {
            return 0
        }
        return -1
    }
    return ret
}

If you're implementing this yourself, don't omit the @objc and NSObject inheritance or you'll get a -1 result from processIsTranslated() every time.