My app can run with a UI and run headless, chosen via a command-line argument. (I don't want to build two separate apps.) When running headless, I'm calling:
[NSApp setActivationPolicy:NSApplicationActivationPolicyProhibited];
during app initialization, and don't show any windows.
This all works fine, and I can run the app headed (via the dock) and headless (via another app passing the command-line argument) at the same time. The little dot shows up next to the dock icon only for the headed app. Good. The problem happens if the headless app is launched first. In that state (no dot in the dock), any clicking on the app icon (or launching via Spotlight or the Finder) does nothing, or sometimes brings up "You can’t open the application “Foo” because it is not responding." Presumably the OS thinks the app is already running headed, and is trying to activate it. Is there a way to convince it to ignore that background app and launch a new instance?
Quitting the background app allows the app to launch normally again from the dock.
I don't want to set LSBackgroundOnly in the plist, because that would require two separate apps unless I changed the setActivationPolicy to NSApplicationActivationPolicyRegular in the case of the headed app. But I've read that doing that causes various other bugs, like the menu bar not always showing up.
Any ideas?
I'm on OS 10.10.5 (the oldest OS I need to support). Thanks for any help!
Update: I just noticed that when clicking on the dock and it appears to do nothing, if there are no app windows open I can see that it actually unhides my app's main window (which was created hidden) but doesn't bring it to the front (presumably it notices that NSApplicationActivationPolicyProhibited is set, though that wasn't enough to prevent it from showing the window!).
Update 2: At this point, I'd settle for a way to notify the user that the reason the app isn't launching is that they need to quit the other app that has sublaunched the headless process. Of course this code would need to be in the headless app, since the headed doesn't even launch.
It looks like you can call setActivationPolicy from applicationShouldHandleReopen and set the policy back to NSApplicationActivationPolicyRegular at that time. I made a test app with the following code and it seems to behave as you describe you would like it to above (although I've only run it on 10.11.5):
@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
func applicationDidFinishLaunching(aNotification: NSNotification) {
if NSUserDefaults.standardUserDefaults().stringForKey("background") == "true" {
NSApp.setActivationPolicy(.Prohibited)
print("launched in background")
}
}
func applicationShouldHandleReopen(sender: NSApplication, hasVisibleWindows flag: Bool) -> Bool {
NSApp.setActivationPolicy(.Regular)
return true
}
}