Set MacOS X menubar app to launch at startup - cocoa

Question

I have a sandboxed menubar application (no dock icon) that in it's preferences window allows the user to check a checkbox to have the app launch at login. I used to use the LSSharedFileList api, but as this is not allowed anymore for sandboxed apps, I've migrated to using SMLoginItemSetEnabled. What I've found is that although the app will launch at login, as expected, if I go back into the Preferences and uncheck and re-check the launch at login checkbox, I get a second instance of my menubar app launched.
Here's my helper app code (in its app delegate):
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
NSString * path = [[[[[[NSBundle mainBundle] bundlePath] stringByDeletingLastPathComponent]
stringByDeletingLastPathComponent]
stringByDeletingLastPathComponent]
stringByDeletingLastPathComponent];
[[NSWorkspace sharedWorkspace] launchApplication:path];
[NSApp terminate:nil];
}
Here is the code in my preferences window (main app):
- (IBAction)toggleLoginStatus:(NSButton*)sender{
if(!SMLoginItemSetEnabled((__bridge CFStringRef)#"myAppBundleIdentifier", (BOOL)[sender state])){
NSLog(#"Dagnabit!");
}
}
After the second instance launches, unchecking/re-checking the checkbox does not launch anymore instances. Does anyone have any idea what's going on?
Thanks

Answer 1

I've found the answer. None of the tutorials I looked at mentioned this, but in the docs for SMLoginItemEnabled says this:
The Boolean enabled state of the helper application. This value is
effective only for the currently logged in user. If true, the helper
application will be started immediately (and upon subsequent logins)
and kept running. If false, the helper application will no longer be
kept running.
So I'll have to check if the app is running already before allowing the helper to launch it.

Answer 2

I spent almost two days figuring out this. Finally dropped the idea to support launch at login.
Although it is just a case of Yes or no in the Front end, developer on the other hand has to spent huge amount of time(Adding a helper application and doing all those project settings in both the apps). The process in early days (before sandboxing)was pretty much simpler than it is now.
Also when the application is added to the 'launch at login' list, there is no way to verify because the application is not listed in system preferences -> users -> login items, as it was before sand boxing.
I am also facing a strange problem where I added helper app to the launch at login and then uninstalled the helper, but the activity monitor still shows helper app in the list, after each reboot.
Lets hope apple adds something like LaunchAtLoginController in coming future.