Question

like NSPanel displayed after a button clicked in the NSWindow.

I looked for a lot but there is no simple example.
Thanks for any help.

Answer 1

It can be done like this:

-(IBAction)showButtonAction:(id)sender {
    [[NSApplication sharedApplication] beginSheet:panelOutlet
                                   modalForWindow:self.window
                                    modalDelegate:self
                                   didEndSelector:@selector(sheetDidEnd:returnCode:contextInfo:)
                                      contextInfo:nil];
}

Attention:

Don’t forget to uncheck NSPanel‘s Visible At Launch checkbox in
Attributes Inspector and Release When Closed if you will use this panel not once.

Result: