When calling TransformProcessType(), the app menu doesn't show up

Question

If you call TransformProcessType() like this :

ProcessSerialNumber psn = { 0, kCurrentProcess }; 
(void) TransformProcessType(&psn, kProcessTransformToForegroundApplication);

Then the cocoa app menu doesn't show up unless you call this early enough in your app (eg. in applicationWillFinishLaunching).

Answer 1

I asked Apple for help and they helped me very well. Quote :

The reason why the menu bar isn't show when you call TransformProcessType is that your app is already the active app (that is, [[NSRunningApplication currentApplication] isActive] returns YES) and the menu bar for an app is shown when the app is activated

This is their workaround :

- (void)transformStep1 {
    for (NSRunningApplication * app in [NSRunningApplication runningApplicationsWithBundleIdentifier:@"com.apple.finder"]) {
        [app activateWithOptions:NSApplicationActivateIgnoringOtherApps];
        break;
    }
    [self performSelector:@selector(transformStep2) withObject:nil afterDelay:0.1];
}

- (void)transformStep2
{
    ProcessSerialNumber psn = { 0, kCurrentProcess }; 
    (void) TransformProcessType(&psn, kProcessTransformToForegroundApplication);

    [self performSelector:@selector(transformStep3) withObject:nil afterDelay:0.1];
}

- (void)transformStep3
{
    [[NSRunningApplication currentApplication] activateWithOptions:NSApplicationActivateIgnoringOtherApps];
}

Answer 2

Here is how I made it working.

BOOL MakeAppForeground()
{
    BOOL bSuccess = TranformAppToState(kProcessTransformToForegroundApplication);

    if(bSuccess)
    {
         bSuccess = (SetSystemUIMode(kUIModeNormal, 0) == 0);
        [NSApp activateIgnoringOtherApps:YES];
    }

    return bSuccess;
}

BOOL MakeAppBackground()
{
    return TranformAppToState(kProcessTransformToBackgroundApplication);
}

BOOL TranformAppToState(ProcessApplicationTransformState newState)
{
    ProcessSerialNumber psn = { 0, kCurrentProcess };
    OSStatus transformStatus = TransformProcessType(&psn, newState);

    if((transformStatus != 0))
    {
        NSError *error = [NSError errorWithDomain:NSOSStatusErrorDomain code:transformStatus userInfo:nil];
        NSLog(@"TranformAppToState: Unable to transform App state. Error - %@",error);
    }

    return (transformStatus == 0);
}