How do i implement a message box in a Cocoa application?

Question

I have implemented delete functionality in cocoa application now i want to show one meesage box when user click on delete button.

Answer 1

Take a look at NSAlert, which has a synchronous -runModal method:

NSAlert *alert = [[[NSAlert alloc] init] autorelease];
[alert setMessageText:@"Hi there."];
[alert runModal];

As Peter mentions, a better alternative is to use the alert as a modal sheet on the window, e.g.:

[alert beginSheetModalForWindow:window
              modalDelegate:self
             didEndSelector:@selector(alertDidEnd:returnCode:contextInfo:)
                contextInfo:nil];

Buttons can be added via -addButtonWithTitle::

[a addButtonWithTitle:@"First"];
[a addButtonWithTitle:@"Second"];

The return code tells you which button was pressed:

- (void) alertDidEnd:(NSAlert *)a returnCode:(NSInteger)rc contextInfo:(void *)ci {
    switch(rc) {
        case NSAlertFirstButtonReturn:
            // "First" pressed
            break;
        case NSAlertSecondButtonReturn:
            // "Second" pressed
            break;
        // ...
    }
}