版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/cuihaiyang/article/details/60764707
拷贝的一个项目运行报错：
2017-03-07 14:44:57.906 Zenithcp[54472:2455909] *** Assertion failure in -[UIApplication _runWithMainScene:transitionContext:completion:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3600.5.2/UIApplication.m:3679
错误原因：
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];//自定义了window，但是没有设置rootViewController
[self.window makeKeyAndVisible];
[self.window.rootViewController presentViewController:surfboard animated:NO completion:nil];
return YES;
}UINavigationController *indexViewCr=[[UIStoryboard storyboardWithName:@"Main" bundle:nil] instantiateViewControllerWithIdentifier:@"Nav"];
keyWindow.rootViewController = indexViewCr;