applicationShouldTerminateAfterLastWindowClosed: does not seem to work when the red x is used to close my Cocoa app

Question

I have a small OSX Cocoa app that just bring up an IKPicutreTaker and saves the picture to a file if one is set. I use applicationShouldTerminateAfterLastWindowClosed: to close the application when the pictureTaker is closed. This all works fine when I either set(this is done when you have picked the picture you want) or when you hit cancel, but when I click on the red arrow in the top left of the windows, the application does not quit when the window is closed this way. Is this intended functionality or am I doing something wrong (not setting some flag?). Also, is there some way to disable this button?

Answer 1

Clicking the red button does not close an application, partly because that verb does not go with that noun. The red button closes the window it's on; it does not quit your application. (An application can and will often have multiple windows on Mac OS X.)

That's where applicationShouldTerminateAfterLastWindowClosed: comes in. Whenever the user closes the last window on the screen (whether by clicking the red button, by choosing Close from the File menu, or by some other means), the NSApplication object will send an applicationShouldTerminateAfterLastWindowClosed: message to its delegate, to ask it whether the application should terminate. If the delegate responds to the message by returning YES, then the application will terminate itself.

You don't say exactly how you're “using” applicationShouldTerminateAfterLastWindowClosed:. If you're just sending it to some object, that's not going to work, because you're asking a question (“should the application terminate after the last window is closed?”) and then ignoring the answer. If you implement the method in an object, but that object isn't the application's delegate, that won't work either—the application object only sends that message to its delegate.

You need to implement the method in your delegate, and return YES when it is appropriate for the application to terminate when the user closes its last window.