Error building from 5 to 6 IOS - objective-c

Question

I have IPad application for IOS 5.1, now i'm trying to build it for 6.0, and get an error:
* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason:
-[NSFileManager copyItemAtPath:toPath:error:]: source path is nil'
"
i found where is this problem, but i don't know how to correct it
in my AppDelegate
-(void)copyFileWithName:(NSString*)name Extension:(NSString*)extension ToDir:(NSString*)dirName withName:(NSString*)newName
{
NSString *folderPath = dirName;
NSString *filePathDocTxt = [folderPath stringByAppendingPathComponent:[NSString stringWithFormat:#"%#.%#", newName, extension]];
NSString *filePathBundleTxt = [[NSBundle mainBundle] pathForResource:name ofType:extension];
//when i comment these two lines, my code compiles success, but i need these code
if(![[NSFileManager defaultManager] fileExistsAtPath:filePathDocTxt])
[[NSFileManager defaultManager] copyItemAtPath:filePathBundleTxt toPath:filePathDocTxt error:nil];
}

Answer 1

well the error is source path for the copyItemAtPath method is nil.
Since you copy from the bundle (your app) to another folder that implies that the file is not in the target.
make sure the file you attempt to copy is there and correctly added to the target (in Xcode)
to resolve the crash add an if to exclude copying if the item isn't there / assert it
NSString *filePathBundleTxt = [[NSBundle mainBundle] pathForResource:name ofType:extension];
assert(filePathBundleTxT);