UIStoryboard和UIResponder

//获取someboard中InitialViewController

UIStoryboard *story = [UIStoryboard storyboardWithName:@"someboard" bundle:nil];

self.window.rootViewController = [story instantiateInitialViewController];

//获取someboard中identity为storyboardID的控制器

UIStoryboard *story = [UIStoryboard storyboardWithName:@"someboard" bundle:nil];

self.window.rootViewController = [story instantiateViewControllerWithIdentifier:@"storyboardID"];

- (BOOL)becomeFirstResponder; // 成为第一响应者（文本框获得焦点并调出键盘）