objective-c - NSPopover 无法正常工作

Question

我像这样以编程方式创建一个 NSPopover：

    popViewController *controller = [[popViewController alloc] initWithNibName:@"popViewController" bundle:nil];

    NSPopover *thePopover = [[NSPopover alloc] init];

    [thePopover setBehavior:NSPopoverBehaviorTransient];
    [thePopover setAnimates:YES];
    [thePopover setContentViewController:controller];

    [thePopover showRelativeToRect: [[sender superview] bounds] ofView:[sender superview] preferredEdge:NSMaxXEdge];  

当调用具有此代码的函数时，会出现 NSPopover，但是当我单击屏幕上的某个位置时，即使在 NSPopover 内部，它也会关闭，并且我在控制台中收到以下错误消息：

customMenuItem[8530] <Error>: kCGErrorIllegalArgument: _CGSFindSharedWindow: WID 1998
Jul 23 14:55:46 ThousandSunny.local customMenuItem[8530] <Error>: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
Jul 23 14:55:46 ThousandSunny.local customMenuItem[8530] <Error>: kCGErrorIllegalArgument: CGSRemoveWindowFromWindowMovementGroup: Invalid window  

出了什么问题？