iOS 任何位置轻松控制自己当前想显示的控制器

#import"AppDelegate.h"

//  在控制器内操作根视图

 UIStoryboard *storyboard = [UIStoryboardstoryboardWithName:@"Main"bundle:[NSBundlemainBundle]];

id view = [storyboardinstantiateViewControllerWithIdentifier:@"LoginNav"];

[UIApplication sharedApplication].keyWindow.rootViewController = view;

//  在AppDelegate代理方法内控制根视图

UIStoryboard *storyboard = [UIStoryboardstoryboardWithName:@"Main"bundle:[NSBundlemainBundle]];

id view = [storyboardinstantiateViewControllerWithIdentifier:@"LoginNav"];

self.window.rootViewController = view;