What characters are allowed in a iOS file name?

Question

I'm looking for a way to make sure a string can be used as a file name under iOS. I'm currently in the section of the code that deletes incompatible characters. I'm wondering if I'm doing it right.

NSString *filename = @"A file name"; fileName = [fileName stringByTrimmingCharactersInSet: [NSCharacterSet controlCharacterSet]]; fileName = [fileName stringByTrimmingCharactersInSet: [NSCharacterSet newlineCharacterSet]]; 

I'm also wondering if there's already a method that validates a string as a file name.

Thank you for your advice!

Answer 1

Use RegEx:

NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:@"[^a-zA-Z0-9_]+" options:0 error:nil]; filename = [regex stringByReplacingMatchesInString:filename options:0 range:NSMakeRange(0, filename.length) withTemplate:@"-"]; 

Answer 2

I find this to be cleaner and probably much more performant. This is based on Angel Naydenov's solution, but first constructing Character set with all invalid characters and then calling components(separatedBy:) just once.

Swift 3 & 4

var invalidCharacters = CharacterSet(charactersIn: ":/") invalidCharacters.formUnion(.newlines) invalidCharacters.formUnion(.illegalCharacters) invalidCharacters.formUnion(.controlCharacters)  let newFilename = originalFilename     .components(separatedBy: invalidCharacters)     .joined(separator: "") 

Swift 2

let invalidCharacters = NSMutableCharacterSet(charactersInString: ":/") invalidCharacters.formUnionWithCharacterSet(NSCharacterSet.newlineCharacterSet()) invalidCharacters.formUnionWithCharacterSet(NSCharacterSet.illegalCharacterSet()) invalidCharacters.formUnionWithCharacterSet(NSCharacterSet.controlCharacterSet())  let filename = originalFilename     .componentsSeparatedByCharactersInSet(invalidCharacters)     .joinWithSeparator("")