App is crashing in a certain line, Why? - ios4

Question

My real code is full of NSLog's,
the following line is the reason for he crash but I don't understand why
NSString *newDir = [documentsDirectory
stringByAppendingPathComponent:file];
Here is the whole method:
- (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];
}
As mentioned the NSLog print of documentsDirectory and file are:
documentsDirectory: /Users/admin/Library/Application Support/iPhone
Simulator/4.3/Applications/D5AB6F90-0420-4A66-B141-D27AB2C11C3C/Documents
file://localhost/Users/admin/Library/FotoAppFotos/Audio/
The whole crash log is:
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'
Thank you for any help and presumption in advance

Answer 1

The hint comes from:
[NSURL length]: unrecognized selector sent to instance
If you are working on iOS, sorry to tell that :
This method is unimplemented in iOS, so it performs no operation.
Somebody has similar problem .