1.删除info.plist文件中 Main storyboard file base name项
该项用于引导程序打开Main的 storyboard 文件
2.在appdelegate中，
application:(UIApplication *)application
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 函数创建window，即
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
3.在appdelegate中，
application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 函数�中，显示window
[self.window makeKeyAndVisible]; //显示窗口
