Question

Is there way to take a NSString and turn it into a safe version that can be used as a filename to save to the user Documents directory on the iPhone.

I’m currently doing something like this:

NSString *inputString = @"This is sample text which may have funny chars and spaces in.";

NSInteger len = [inputString length];        
NSString *newFilename = [[inputString substringToIndex:MIN(20, len)] stringByAppendingPathExtension:@"txt"];

This currently leaves me with something like:

This is sample text .txt

Need to make sure characters that are not allowed in filenames and stripped out too.

Answer 1

You’ll probably end up with some regex or something. Simply because it’s too dangerous to use a except-filter (you may miss some illegal chars).

Therefor I’ld recommend you to use RegexKitLite (http://regexkit.sourceforge.net/RegexKitLite/), combined with the following line of code:

inputString = [inputString stringByReplacingOccurencesOfRegex:@"([^A-Za-z0-9]*)" withString:@""];

This will replace all characters except A-Z, a-z and 0-9 =)!