How to make an NSString path (file name) safe

Question

I'm using very tricky fighting methods :) to make a string like Fi?le*/ Name safe for using as a file name like File_Name. I'm sure there is a cocoa way to convert it. And I'm sure the best place to ask is here :)

Thank you!

Answer 1

This will remove all invalid characters anywhere in the filename based on Ismail's invalid character set (I have not verified how complete his set is).

- (NSString *)_sanitizeFileNameString:(NSString *)fileName {
    NSCharacterSet* illegalFileNameCharacters = [NSCharacterSet characterSetWithCharactersInString:@"/\\?%*|\"<>"];
    return [[fileName componentsSeparatedByCharactersInSet:illegalFileNameCharacters] componentsJoinedByString:@""];
}

Credit goes to Peter N Lewis for the idea to use componentsSeparatedByCharactersInSet:
NSString - Convert to pure alphabet only (i.e. remove accents+punctuation)

Answer 2

Unless you're explicitly running the shell or implicitly running the shell by using a function such as popen or system, there's no reason to escape anything but the pathname separator.

You may also want to enforce that the filename does not begin with a full stop (which would cause Finder to hide the file) and probably should also enforce that it is not empty and is fewer than NAME_MAX characters* long.

*syslimits.h says bytes, but if you go through File Manager, it's characters. I'm not sure which is right for Cocoa.

Answer 3

Solution in Swift 4

extension String {
    var sanitizedFileName: String {
        return components(separatedBy: .init(charactersIn: "/\:\?%*|\"<>")).joined()
    }
}

Usage:

"https://myurl.com".sanitizedFileName // = httpsmyurl.com