Xcode7出现Assertion failure in -[UIApplication _runWithMainScene:transitionContext:completion:]

原文链接：http://blog.csdn.net/hjaycee/article/details/48546405

完整报错内容：

Assertion failure in -[UIApplication _runWithMainScene:transitionContext:completion:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit/UIKit-3505.16/UIApplication.m:3294

原因：

Xcode7需要所有UIWindow必须有一个rootViewController

解决办法：

UIWindow *window = [[UIWindowalloc]initWithFrame:[UIScreenmainScreen].bounds];
window.rootViewController = [UIViewController new];