writeToFile does not work after removeItemAtPath

Question

I have an iOS app that at times needs to store UIImage objects locally.

I am using [UIImagePNGRepresentation(image) writeToFile:full_path options:NSAtomicWrite error:nil]; to save the image and [file_manager removeItemAtPath:full_path error:NULL]; to delete the file.

This all works great, however, whenever I delete a file, should I decide to save a new file (which just so happens to have the same name as the old file), the save code doesn't work and returns the following error:

: ImageIO: CGImageReadCreateDataWithMappedFile 'open' failed error = 2 (No such file or directory)

: ImageIO: CGImageReadCreateDataWithMappedFile 'open' failed error = 2 (No such file or directory)

: ImageIO: PNG zlib error

So heres what I don't get, why can't I save a file with the same name as the old file, after I have deleted the old file?

The reason I ask this, is that, my app will save certain image files and then when they are no longer needed, my app will delete them. However, there are times when my app needs the image files again (could be a few hours after deletion or a few weeks). When this happens, my app will load the appropriate image data and then try to save it. And thats when the error occurs.

Whats going wrong here?

Thanks for your time, Dan.

UPDATE - Here are the methods I have setup to save/access and delete my image files

-(void)save_local_image:(UIImage *)image :(NSString *)file_name {

    // Get the app documents directory link.
    NSString *documents = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

    // Add the new file name to the link.
    NSString *database_link = [[NSString alloc] initWithString:[documents stringByAppendingPathComponent:file_name]];

    // Save the image data locally.
    [UIImagePNGRepresentation(image) writeToFile:database_link options:NSAtomicWrite error:nil];
}

-(UIImage *)get_local_image:(NSString *)file_name {

    // Create the return data.
    UIImage *image_data = nil;

    // Get the app documents directory.
    NSArray *directory = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] error:NULL];

    // Only check for data if at least
    // one file has been saved locally.

    if ([directory count] > 0) {

        // Loop through the different local files.

        for (NSString *path in directory) {

            // Get the full local file URL.
            NSString *full_path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:path];

            // Get the range of the file name.
            NSRange range = [full_path rangeOfString:file_name];

            // Get the image data if it exists.

            if ((range.location != NSNotFound) || (range.length == [file_name length])) {

                // Load the image file in.
                image_data = [UIImage imageWithContentsOfFile:full_path];

                break;
            }
        }
    }

    return image_data;
}

-(void)delete_local_image:(NSString *)file_name {

    // Get the app documents directory.
    NSArray *directory = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] error:NULL];

    // Only check for data if at least
    // one file has been saved locally.

    if ([directory count] > 0) {

        // Loop through the different local files.

        for (NSString *path in directory) {

            // Get the full local file URL.
            NSString *full_path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:path];

            // Get the range of the file name.
            NSRange range = [full_path rangeOfString:file_name];

            // Delete the local image data if it exists.

            if ((range.location != NSNotFound) || (range.length == [file_name length])) {

                NSError *testError = nil;

                // Delete the image file.
                NSFileManager *file_manager = [[NSFileManager alloc] init];
                BOOL success = [file_manager removeItemAtPath:full_path error:&testError];

                NSLog(@"%d", success);

                if (testError != nil) {
                    NSLog(@"%@", testError.localizedDescription);
                }


                break;
            }
        }
    }
}

Answer 1

I am using this to save and read:

- (void) saveImageToFile:(NSString *) urlImg withNameNumber:(int)numberName andQuestionId:(int) questionID
{

 NSString* documentsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
 NSString* foofile = [documentsPath stringByAppendingPathComponent:[NSString stringWithFormat:@"gallery%d%d.jpg",numberName,questionID]];
 BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:foofile];

 if (!fileExists) {
    NSData *tempImgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@%@",@"https://testurl/",urlImg]]];
    NSString *filename = [NSString stringWithFormat:@"gallery%d%d.jpg",numberName,questionID];
    NSString *imagePath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0] stringByAppendingPathComponent:filename];
    [tempImgData writeToFile:imagePath atomically:YES];
 }
}

-(UIImage*) readImageFromFile:(int)numberName andQuestionId:(int) questionID
{
  NSString * documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];

  return [UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@/gallery%d%d.jpg",documentsDirectoryPath,numberName,questionID]];
}