title: App is crashing in a certain line, Why?
body: <p>My real code is full of NSLog's,
  the following  line is the reason for he crash but I don't understand why</p>
  
  <blockquote>
    <p>NSString *newDir = [documentsDirectory
    stringByAppendingPathComponent:file];</p>
  </blockquote>
  
  <p>Here is the whole method:</p>
  
  <pre><code> - (void)viewDidLoad {  
  
      NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);   
      NSString *documentsDirectory = [paths objectAtIndex:0];
      NSFileManager *fileManager = [NSFileManager defaultManager];    
      NSArray* newArray= [[NSArray alloc]init];   
      newArray=  [fileManager contentsOfDirectoryAtURL:[NSURL fileURLWithPath:@"/Users/admin/Library/FotoAppFotos/"]
      includingPropertiesForKeys:[NSArray arrayWithObject:NSURLNameKey]                                        options:NSDirectoryEnumerationSkipsHiddenFiles error:nil];         
      categories= [NSMutableArray arrayWithArray: newArray];
  
          for(NSString *file in categories) {  
  
          NSString *newDir = [documentsDirectory stringByAppendingPathComponent:file]; // in this line the app crashes        
          [categories addObject:newDir]; //categories         
          } 
          [super viewDidLoad]; 
      }
  </code></pre>
  
  <p>As mentioned the NSLog print of documentsDirectory and file are: </p>
  
  <blockquote>
    <p>documentsDirectory: /Users/admin/Library/Application Support/iPhone
    Simulator/4.3/Applications/D5AB6F90-0420-4A66-B141-D27AB2C11C3C/Documents</p>
    
    <p>file://localhost/Users/admin/Library/FotoAppFotos/Audio/</p>
  </blockquote>
  
  <p>The whole crash log is: </p>
  
  <pre><code>2011-11-09 09:21:42.989 TestTest[543:207] -[NSURL length]: unrecognized selector sent to instance 0x5c07df0
  2011-11-09 09:21:42.992 TestTest[543:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSURL length]: unrecognized selector sent to instance 0x5c07df0'
  *** Call stack at first throw:
  (
      0   CoreFoundation                      0x0102b5a9 __exceptionPreprocess + 185
      1   libobjc.A.dylib                     0x0117f313 objc_exception_throw + 44
      2   CoreFoundation                      0x0102d0bb -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
      3   CoreFoundation                      0x00f9c966 ___forwarding___ + 966
      4   CoreFoundation                      0x00f9c522 _CF_forwarding_prep_0 + 50
      5   Foundation                          0x0002b1ad -[NSPathStore2 stringByAppendingPathComponent:] + 211
      6   TestTest                            0x00003244 -[Produktpalette viewDidLoad] + 535
      7   UIKit                               0x0036f089 -[UIViewController view] + 179
      8   UIKit                               0x0060ca40 -[UIPopoverController _setupIncomingViewController:presenting:animated:] + 143
      9   UIKit                               0x0060be26 -[UIPopoverController initWithContentViewController:] + 321
      10  TestTest                            0x00002540 -[TestTestViewController produktpalette:] + 151
      11  UIKit                               0x002bf4fd -[UIApplication sendAction:to:from:forEvent:] + 119
      12  UIKit                               0x004d1cc3 -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 156
      13  UIKit                               0x002bf4fd -[UIApplication sendAction:to:from:forEvent:] + 119
      14  UIKit                               0x0034f799 -[UIControl sendAction:to:forEvent:] + 67
      15  UIKit                               0x00351c2b -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 527
      16  UIKit                               0x003507d8 -[UIControl touchesEnded:withEvent:] + 458
      17  UIKit                               0x002e3ded -[UIWindow _sendTouchesForEvent:] + 567
      18  UIKit                               0x002c4c37 -[UIApplication sendEvent:] + 447
      19  UIKit                               0x002c9f2e _UIApplicationHandleEvent + 7576
      20  GraphicsServices                    0x01983992 PurpleEventCallback + 1550
      21  CoreFoundation                      0x0100c944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
      22  CoreFoundation                      0x00f6ccf7 __CFRunLoopDoSource1 + 215
      23  CoreFoundation                      0x00f69f83 __CFRunLoopRun + 979
      24  CoreFoundation                      0x00f69840 CFRunLoopRunSpecific + 208
      25  CoreFoundation                      0x00f69761 CFRunLoopRunInMode + 97
      26  GraphicsServices                    0x019821c4 GSEventRunModal + 217
      27  GraphicsServices                    0x01982289 GSEventRun + 115
      28  UIKit                               0x002cdc93 UIApplicationMain + 1160
      29  TestTest                            0x00001c2a main + 84
      30  TestTest                            0x00001bcd start + 53
  )
  terminate called after throwing an instance of 'NSException'
  </code></pre>
  
  <p>Thank you for any help and presumption in advance</p>