Xcode 7.2.1中运行Xcode 5中的Empty工程导致崩溃

1.现象

2016-05-06 10:46:56.090 Demo[1138:58497] *** Assertion failure in -[UIApplication _runWithMainScene:transitionContext:completion:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3512.30.14/UIApplication.m:3315
2016-05-06 10:46:56.097 Demo[1138:58497] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Application windows are expected to have a root view controller at the end of application launch'
*** First throw call stack:
(
	0   CoreFoundation                      0x0000000105807e65 __exceptionPreprocess + 165
	1   libobjc.A.dylib                     0x000000010527edeb objc_exception_throw + 48
	2   CoreFoundation                      0x0000000105807cca +[NSException raise:format:arguments:] + 106
	3   Foundation                          0x0000000104eca4de -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 198
	4   UIKit                               0x00000001038e8218 -[UIApplication _runWithMainScene:transitionContext:completion:] + 3122
	5   UIKit                               0x00000001038e4e7b -[UIApplication workspaceDidEndTransaction:] + 188
	6   FrontBoardServices                  0x00000001086ea754 -[FBSSerialQueue _performNext] + 192
	7   FrontBoardServices                  0x00000001086eaac2 -[FBSSerialQueue _performNextFromRunLoopSource] + 45
	8   CoreFoundation                      0x0000000105733a31 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
	9   CoreFoundation                      0x000000010572995c __CFRunLoopDoSources0 + 556
	10  CoreFoundation                      0x0000000105728e13 __CFRunLoopRun + 867
	11  CoreFoundation                      0x0000000105728828 CFRunLoopRunSpecific + 488
	12  UIKit                               0x00000001038e47cd -[UIApplication _run] + 402
	13  UIKit                               0x00000001038e9610 UIApplicationMain + 171
	14  Demo                                0x00000001035cf9cf main + 111
	15  libdyld.dylib                       0x00000001066bb92d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

2.原因

　　由于没有设置rootViewController。

3.解决方案

　　设置rootViewController即可。

4.相关文档

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