崩溃原因

crash：

Assertion failure in 

-[UIApplication _runWithMainScene:transitionContext:completion:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-

 （

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', `enter code here`reason: 'Application windows are expected to have a root

view controller at the end of application launch'

*** First throw call stack:

）

 

 尝试解决方案一：

//  *************代码做调整，加入到下一个loop周期中，再次运行代码，程序正常。******//

 

- (void)applicationDidBecomeActive:(UIApplication *)application {    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.       //crash in ios9    _testWindow = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];    _testWindow.hidden = NO;       //ok    //    dispatch_async(dispatch_get_main_queue(), ^{    //        _testWindow = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];    //        _testWindow.hidden = NO;    //    });      }

Or

 

 尝试解决方案二：

 　　Xcode7 需要所有的窗口都必须有根控制器

 

XCODE 7 requires that all the Windows must have a rootViewController You can use easy:

 

UIViewController* vc = [[UIViewController alloc]initWithNibName:nil bundle:nil];  self.window.rootViewController = vc;

 

It's working good if you need to use only UIWindow (for easy examples from any Tutorials - before Xcode 7)!