Crashing iOS app after creating a new view

Question

I'm just starting to learn creating iOS apps and so I'm just a noob in it. Especially because of the different approach it has on handling navigation and interaction between UI and Code. :)

Ok I'm using xCode 5 with SDK version 7. I created a single view application and it gave me a .storyboard file which I guess replaces the .xib which used to be there when I watch tutorial videos.

So I designed a simple UI as the main view and now I want to have another view as the landing view. So it should come in before the main view. I went ahead and from New File... I created an Objective-C class which is a subclass of UIViewController and named it Detail . Surprisingly it gave me a .xib file again. Fair enough. Then I just put a simple input in the UI to just preview it.

Then from Project Settings, in the General tab, I changed the Main Interface to match the new .xib file I created. But when I launched the application, it crashed and I don't know what the problem is.

Here is the stack trace:

2013-11-27 18:31:21.735 TestViewSwitching[10123:70b] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[<UIApplication 0x8b35dc0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key view.'
*** First throw call stack:
(
    0   CoreFoundation                      0x0174c5e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x014bb8b6 objc_exception_throw + 44
    2   CoreFoundation                      0x017dc6a1 -[NSException raise] + 17
    3   Foundation                          0x0117c9ee -[NSObject(NSKeyValueCoding) setValue:forUndefinedKey:] + 282
    4   Foundation                          0x010e8cfb _NSSetUsingKeyValueSetter + 88
    5   Foundation                          0x010e8253 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 267
    6   Foundation                          0x0114a70a -[NSObject(NSKeyValueCoding) setValue:forKeyPath:] + 412
    7   UIKit                               0x004cba15 -[UIRuntimeOutletConnection connect] + 106
    8   libobjc.A.dylib                     0x014cd7d2 -[NSObject performSelector:] + 62
    9   CoreFoundation                      0x01747b6a -[NSArray makeObjectsPerformSelector:] + 314
    10  UIKit                               0x004ca56e -[UINib instantiateWithOwner:options:] + 1417
    11  UIKit                               0x004cc2fb -[NSBundle(UINSBundleAdditions) loadNibNamed:owner:options:] + 165
    12  UIKit                               0x002293bb -[UIApplication _loadMainNibFileNamed:bundle:] + 58
    13  UIKit                               0x002296e9 -[UIApplication _loadMainInterfaceFile] + 245
    14  UIKit                               0x0022828f -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 543
    15  UIKit                               0x0023c87c -[UIApplication handleEvent:withNewEvent:] + 3447
    16  UIKit                               0x0023cde9 -[UIApplication sendEvent:] + 85
    17  UIKit                               0x0022a025 _UIApplicationHandleEvent + 736
    18  GraphicsServices                    0x036df2f6 _PurpleEventCallback + 776
    19  GraphicsServices                    0x036dee01 PurpleEventCallback + 46
    20  CoreFoundation                      0x016c7d65 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53
    21  CoreFoundation                      0x016c7a9b __CFRunLoopDoSource1 + 523
    22  CoreFoundation                      0x016f277c __CFRunLoopRun + 2156
    23  CoreFoundation                      0x016f1ac3 CFRunLoopRunSpecific + 467
    24  CoreFoundation                      0x016f18db CFRunLoopRunInMode + 123
    25  UIKit                               0x00227add -[UIApplication _run] + 840
    26  UIKit                               0x00229d3b UIApplicationMain + 1225
    27  TestViewSwitching                   0x0000211d main + 141
    28  libdyld.dylib                       0x01d7670d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

This process in Android is pretty straight forward, but I don't know why Apple tries to make everything harder for developers. They couldn't just set up a type which generates a new view ready to go?

Answer 1

@Miro Markarian，您可以检查.xib文件中的视图出口。它可能已断开连接或损坏。通常是由于这个原因而引起的。请尝试将视图控制器视图的出口添加到.xib视图中。

Answer 2

主视图控制器的.xib上的视图出口未正确连接到其file owner 。