Closing Mac application (clicking red cross on top) and reopening by clicking dock icon

Question

When I close my Mac application (by clicking red cross button on window top bar) the app icon stays in the dock at the bottom. Now this is normal behaviour. When user click

Answer 1

Implement the method

- (BOOL)applicationShouldTerminateAfterLastWindowClosed:(NSApplication *)sender
{ 
return NO; 
}

in your app delegate

Your app will hang around after the window is closed and then if you implement

- (void)applicationDidBecomeActive:(NSNotification *)aNotification
{
//dock icon has just been clicked , or cmd-tabbed into
}

in the app delegate

You can do things when the icon is clicked such as open a new or old window if you need to

See http://developer.apple.com/library/mac/#documentation/cocoa/reference/NSApplicationDelegate_Protocol/Reference/Reference.html for other relevant application events

Answer 2

I think that the answers above aren't fully correct, to achieve this you should override applicationShouldHandleReopen(_:hasVisibleWindows:) https://developer.apple.com/reference/appkit/nsapplicationdelegate/1428638-applicationshouldhandlereopen

Answer 3

If you are still concerned how to reopen the window that you have closed, use this method:

- (BOOL)applicationShouldHandleReopen:(NSApplication *)theApplication hasVisibleWindows:(BOOL)flag {

[window makeKeyAndOrderFront:self];

return YES;
}

You can use this to handle clicks on the applications icon in the dock.

For further information check out the NSApplicationDelegate Protocol Reference.

Here is the documentation:

http://developer.apple.com/library/mac/#documentation/cocoa/reference/NSApplicationDelegate_Protocol/Reference/Reference.html

Hope this helps!

Latest Update:

In latest Xcode 11.4 on MacOS 10.15 with Swift 5.2, this same problem exists in MacOS SwiftUI app. Adding following code inside AppDelegates.swift solves the issue.

func applicationShouldHandleReopen(_ sender: NSApplication, hasVisibleWindows flag: Bool) -> Bool {
    if !flag{
        window.makeKeyAndOrderFront(nil)
    }
    return true
}