How do I access program arguments in Swift?

Question

C and derivatives have argc and argv (and envp) parameters to their entry point functions, but Swift doesn\'t have one proper: top-lev

Answer 1

For Swift 3 you can use this code:

let argc = CommandLine.argc
let argv = UnsafeMutableRawPointer(CommandLine.unsafeArgv).bindMemory(to: UnsafeMutablePointer.self, capacity: Int(CommandLine.argc))

which is equivalent of argc and argv parameters used in Objective-C main function:

int main(int argc, char *argv[])

For older versions of Swift, you can use Process.argc and Process.unsafeArgv or C_ARGC and C_ARGV.

You can pass this variables to UIApplicationMain function in iOS app:

Swift 3:

let argc = CommandLine.argc
let argv = UnsafeMutableRawPointer(CommandLine.unsafeArgv).bindMemory(to: UnsafeMutablePointer.self, capacity: Int(CommandLine.argc))
UIApplicationMain(argc, argv, nil, NSStringFromClass(AppDelegate.self))

previous Swift versions:

UIApplicationMain(Process.argc, Process.unsafeArgv, nil, NSStringFromClass(AppDelegate.self))

or:

UIApplicationMain(C_ARGC, C_ARGC, nil, NSStringFromClass(AppDelegate.self))

Objective-C:

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}