Make a NSAlert the topmost window?

问题

I've created the main window in my application to have these settings:

[self setLevel:kCGDesktopWindowLevel + 1];
[self setCollectionBehavior:
     (NSWindowCollectionBehaviorCanJoinAllSpaces | 
      NSWindowCollectionBehaviorStationary | 
      NSWindowCollectionBehaviorIgnoresCycle)];

It's a very custom window that sort of floats above the desktop.

In addition, it's a menu-bar application (LSUIElement).

Alright, so I need to display an alert if something isn't right. Here's how I'm doing it:

NSAlert *alert = [NSAlert alertWithMessageText:@"" 
                                 defaultButton:@"" 
                               alternateButton:@"" 
                                   otherButton:@"" 
                     informativeTextWithFormat:@""];
[alert runModal];

Of course I have filled in the buttons and other text.

Here's my problem: When my application is not currently the key application, and this alert pops up, it's not a key window. Like this:

See how the window isn't selected? Is there any way around this without changing my whole app window level? Thanks!

回答1:

Have you tried activating your application in the code that displays the alert?

[[NSRunningApplication currentApplication] activateWithOptions:0];

If passing 0 doesn't work, you can pass NSApplicationActivateIgnoringOtherApps as your option, but Apple recommends against it unless really necessary (see docs for NSRunningApplication).

Update: You have activate before running the alert. This works for me in a new app with LSUIElement set:

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSAlert *alert = [NSAlert alertWithMessageText: @"Blah"
                                     defaultButton: @"Blah"
                                   alternateButton: @"Blah"
                                       otherButton: @"Blah"
                         informativeTextWithFormat: @"Blah"];

    [[NSRunningApplication currentApplication] activateWithOptions:NSApplicationActivateIgnoringOtherApps];
    [alert runModal];
}

回答2:

If you want to support 10.5 also. you can use

[[NSApplication sharedApplication] activateIgnoringOtherApps:YES];

回答3:

Forcing an application to move forefront is a rather bad idea. One would probably prefer to make the alert floating over everything using the dedicated NSPanel property 'floatingPanel':

NSPanel* panel = static_cast<NSPanel*>([alert window]);
panel.floatingPanel = YES;

来源：https://stackoverflow.com/questions/5269116/make-a-nsalert-the-topmost-window

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