title: Objective C, Thread 1 Program Received Signal SIGABRT
body: <p>I am trying to compile and run a simple tutorial for an Objective C app using Interface Builder. I am using Xcode 4.0.2 and simulating on iOS (iPhone) 4.3</p>
  
  <p><a href="http://www.switchonthecode.com/tutorials/creating-your-first-iphone-application-with-interface-builder">http://www.switchonthecode.com/tutorials/creating-your-first-iphone-application-with-interface-builder</a></p>
  
  <p>When I build the project, it builds alright but once the app tries to run it crashes with:</p>
  
  <pre><code>int main(int argc, char *argv[])
  {
      NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
      int retVal = UIApplicationMain(argc, argv, nil, @"SimpleUIAppDelegate");
      [pool release];
      return retVal;
  }
  </code></pre>
  
  <p>I get the error on line 4: int retVal = UI...  Thread 1: Program Received Signal "SIGABRT".</p>
  
  <p>If the other files of this project need to be posted for clarity, I can do that.</p>
  
  <p>Thanks!</p>
  
  <p>Edit:</p>
  
  <p>SimpleUIViewController.h:</p>
  
  <pre><code>#import &lt;UIKit/UIKit.h&gt;
  
  @interface SimpleUIViewController : UIViewController &lt;UITextFieldDelegate&gt; {
      UITextField *textInput;
      UILabel *label;
      NSString *name;
  }
  
  @property (nonatomic, retain) IBOutlet UITextField *textInput;
  @property (nonatomic, retain) IBOutlet UILabel *label;
  @property (nonatomic, copy) NSString *name;
  
  - (IBAction)changeGreeting:(id)sender;
  
  @end
  </code></pre>
  
  <p>SimpleUIViewController.m:</p>
  
  <pre><code>#import "SimpleUIViewController.h"
  
  @implementation SimpleUIViewController
  
  @synthesize textInput;
  @synthesize label;
  @synthesize name;
  
  - (IBAction)changeGreeting:(id)sender {
      self.name = textInput.text;
  
      NSString *nameString = name;
      if([nameString length] == 0) {
          nameString = @"Inigo Montoya";
      }
      NSString *greeting = [[NSString alloc] 
                            initWithFormat:@"Hello, my name is %@!", nameString];
      label.text = greeting;
      [greeting release];
  }
  
  - (BOOL)textFieldShouldReturn:(UITextField *)theTextField {
      if(theTextField == textInput) {
          [textInput resignFirstResponder];
      }
      return YES;
  }
  
  - (void)didReceiveMemoryWarning {
      [super didReceiveMemoryWarning]; 
      // Release anything that's not essential, such as cached data
  }
  
  - (void)dealloc {
      [textInput release];
      [label release];
      [name release];
      [super dealloc];
  }
  
  @end
  </code></pre>
  
  <p>Error message:</p>
  
  <pre><code>This GDB was configured as "x86_64-apple-darwin".Attaching to process 2668.
  2011-06-09 11:20:21.662 InterfaceBuilder[2668:207] Unknown class InterfaceBuilderAppDelegate_iPhone in Interface Builder file.
  2011-06-09 11:20:21.666 InterfaceBuilder[2668:207] *** Terminating app due to uncaught     exception 'NSUnknownKeyException', reason: '[&lt;UIApplication 0x4b1a900&gt;     setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key  textInput.'
  *** Call stack at first throw:
  (
      0   CoreFoundation                      0x00dc25a9 __exceptionPreprocess + 185
      1   libobjc.A.dylib                     0x00f16313 objc_exception_throw + 44
      2   CoreFoundation                      0x00dc24e1 -[NSException raise] + 17
      3   Foundation                          0x00794677 _NSSetUsingKeyValueSetter + 135
      4   Foundation                          0x007945e5 -[NSObject(NSKeyValueCoding) setValue:forKey:] + 285
      5   UIKit                               0x0021030c -[UIRuntimeOutletConnection connect] + 112
      6   CoreFoundation                      0x00d388cf -[NSArray makeObjectsPerformSelector:] + 239
      7   UIKit                               0x0020ed23 -[UINib instantiateWithOwner:options:] + 1041
      8   UIKit                               0x00210ab7 -[NSBundle(UINSBundleAdditions) loadNibNamed:owner:options:] + 168
      9   UIKit                               0x0001617a -[UIApplication _loadMainNibFile] + 172
      10  UIKit                               0x00016cf4 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 291
      11  UIKit                               0x00021617 -[UIApplication handleEvent:withNewEvent:] + 1533
      12  UIKit                               0x00019abf -[UIApplication sendEvent:] + 71
      13  UIKit                               0x0001ef2e _UIApplicationHandleEvent + 7576
      14  GraphicsServices                    0x00ffb992 PurpleEventCallback + 1550
      15  CoreFoundation                      0x00da3944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
      16  CoreFoundation                      0x00d03cf7 __CFRunLoopDoSource1 + 215
      17  CoreFoundation                      0x00d00f83 __CFRunLoopRun + 979
      18  CoreFoundation                      0x00d00840 CFRunLoopRunSpecific + 208
      19  CoreFoundation                      0x00d00761 CFRunLoopRunInMode + 97
      20  UIKit                               0x000167d2 -[UIApplication _run] + 623
      21  UIKit                               0x00022c93 UIApplicationMain + 1160
      22  InterfaceBuilder                    0x000027ff main + 127
      23  InterfaceBuilder                    0x00002775 start + 53
      24  ???                                 0x00000001 0x0 + 1
  )
  terminate called after throwing an instance of 'NSException'
  sharedlibrary apply-load-rules all
  Current language:  auto; currently objective-c
  (gdb) 
  </code></pre>
  
  <p>Im new to obj-c, and have absolutely no idea what I'm looking at in regards to that error message. Any help?</p>