Warning: Attempt to present * on * which is already presenting *

Warning: Attempt to present (要被presented的控制器)  on (哪個控制器來presenting) which is already presenting (已經被presenting的控制器)

self: 是被presented出來的控制器,

self.presentingViewController: 看看是誰把self給presenting出來

RPLog(@"%@ - %@", self.presentingViewController, [UIApplication sharedApplication].keyWindow.rootViewController);

打印結果: <RPNavigationController: 0x789d0330> - <RPNavigationController: 0x789d0330>

結論: popover中的控制器, 其實是通過窗口的根控制器presenting出來的, 所以要想窗口的根控制器再presenting其他控制器,需要先dismiss掉原來presenting的控制器,

        否則會出現如下錯誤:

        Warning: Attempt to present <RPNavigationController: 0x790dad10>  on <RPNavigationController: 0x78e76c70> which is already presenting <RPRegionViewController: 0x78f76700>