iOS - Parse list of filenames/directories for a Web URL?

Question

I want to get all filenames and directories from a provided web url so I can easily create links to those files/directories in my app.

I am having trouble figuring out the best way to parse the text file returned when using NSURLSession's 'dataTaskWithRequest' method since it returns all the data for the contents at the url (i.e. permissions, date created, owner, group, etc.).

Here is how I get the data from a Web URL:

    let request = NSURLRequest(URL: url)
    let session = NSURLSession.sharedSession()
    let task = session.dataTaskWithRequest(request) {[weak self] (data, response, error) -> Void in
        print("Data: \(data)")
        print("Response: \(response)")
        print("Error: \(error)")

        if let weakSelf = self, let data = data, let results = NSString(data: data, encoding: NSASCIIStringEncoding)
        {
            ...how do I parse out the file/directory names???...
        }
    }
    task.resume()

Here is an example of string returned from a given URL:

drwxrwxr-x   26 65534    65534       65536 Sep 20 03:29 Movies
drwxrwsr-x    3 0        65534       65536 Jul 09  2013 Network Trash Folder
drwxrwxr-x   41 65534    65534       65536 Aug 24 15:58 TV
drwxrwsr-x    3 0        65534       65536 Jul 09  2013 Temporary Items

I need to be able to easily and accurately parse out the file/directory names ONLY so I can create links to them. Suggestions?

Answer 1

Assuming your strings are separated by new line character, you can address this by following:

Step 1: Add a method to return word in the entire string

- (NSString *)lastComponentFromString:(NSString *)iString {
    NSRange range= [iString rangeOfString: @" " options: NSBackwardsSearch];
    return  [iString substringFromIndex: range.location+1];   
}

Step 2: Add a method to return entire string but last word

- (NSString *)stringAfterRemovingLastComponentFromString:(NSString *)iString {
    NSRange range= [iString rangeOfString: @" " options: NSBackwardsSearch];
    return [iString substringToIndex: range.location];
}

Step 3: Add a method to trim leading and trailing spaces

- (NSString *)trimString:(NSString *)iBaseString {
    return (iBaseString && ![iBaseString isKindOfClass:[NSNull class]] && iBaseString.length > 0) ? [iBaseString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] : nil;
}

Step 4: Add a method for number validation check:

- (BOOL)numberValidation:(NSString *)text {
    NSString *regex = @"^([0-9]*|[0-9]*[.:][0-9]*)$";
    NSPredicate *test = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
    BOOL isValid = [test evaluateWithObject:text];
    return isValid;
}

Step 5: Add a method to take one line at a time, call above methods and return the final folder name. Here we will keep on finding folder until we hit a number.

- (NSString *)folderNameForPathString:(NSString *)iPathString {
    NSString *lastComponent = [self lastComponentFromString:iPathString];
    NSString *remainingString = [self stringAfterRemovingLastComponentFromString:iPathString];
    NSString *finalFolder = @"";

    while (lastComponent.integerValue == 0) {
        NSString *initialSpaceString = [NSString stringWithFormat:@" %@", finalFolder];

    // Check if the next component is a number
    if ([self numberValidation:lastComponent]) {
        lastComponent = @"";
    }
        finalFolder = [lastComponent stringByAppendingString:initialSpaceString];
        lastComponent = [self lastComponentFromString:remainingString];
        remainingString = [self stringAfterRemovingLastComponentFromString:remainingString];
    }

    return [self trimString:finalFolder];
}

Step 6: Finally, parse your server string to get individual strings separate by new line character.

NSString *data =  @"drwxrwxr-x   26 65534    65534       65536 Sep 20 03:29 Movies\ndrwxrwsr-x    3 0        65534       65536 Jul 09  2013 Network Trash Folder\ndrwxrwxr-x   41 65534    65534       65536 Aug 24 15:58 TV\ndrwxrwsr-x    3 0        65534       65536 Jul 09  2013 Temporary Items";

NSArray *lineArray = [data componentsSeparatedByString:@"\n"];
NSMutableArray *folders = [NSMutableArray array];

for (NSString *pathString in lineArray) {
    [folders addObject:[self folderNameForPathString:pathString]];
}

NSLog(@"folders = %@", folders); // This prints - Movies, Network Trash Folder, TV, Temporary Items