Getting the "locked" state of a file on macOS

Question

One can lock a file against deletion, via the Finder's Get Info window.

I need to determine this lock state from within my program. I need a modern (64 bit savvy) C/ObjC/Swift API operation that lets me do that.

Answer 1

It's the NSURLIsUserImmutableKey resource key. Sneaky, because the documentation makes no mention of "lock".

So, to get the lock state, use this code:

- (BOOL)isLocked {
    NSNumber *result;
    if ([self.url getResourceValue:&result forKey:NSURLIsUserImmutableKey error:nil]) {
        return result.boolValue;
    }
    return NO;
}