Error saving data to cache directory (iPhone)

I am trying to save images using the following code:

- (void)writeData{



    if(cacheFileName==nil)

        return;

    if(cacheDirectoryPath==nil)

        return;





    if (![[NSFileManager defaultManager] fileExistsAtPath:[self filePath]]) {        



        NSData *imageData = UIImageJPEGRepresentation(self.image, 0.9);



        NSError *writeError= nil;



        BOOL didWrite =  [imageData writeToFile:[self filePath] options:NSAtomicWrite error:&writeError];



        if(writeError)

            NSLog([writeError localizedDescription]);



        if(didWrite)

            NSLog(@"image saved");

        else

            NSLog(@"image not saved");





    }

}











 - (NSString *)filePath{



    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES); 

    NSString *cacheDirectory = [paths objectAtIndex:0]; 

    NSString *filename = [cacheDirectory stringByAppendingPathComponent:cacheDirectoryPath]; 

    filename = [filename stringByAppendingPathComponent:cacheFileName]; 

    NSLog(filename);



    return filename;



}

I get an error:

2009-06-23 16:39:19.740 XXX[33454:20b] Operation could not be completed. (Cocoa error 4.)

I looked this up and see the error has the following meaning:

NSFileNoSuchFileError = 4,                      // Attempt to do a file system operation on a non-existent file

Which doesn't make sense since the file shouldn't exist.

I have tried writing the png representation and using the convenience method:

- (BOOL)writeToFile:(NSString *)path atomically:(BOOL)flag

I am using similar code to save plists, and they work fine. I am not sure what the problem is. Any ideas?

Source: Tips4all