NSMutableAttributedStringExtension.swift

extension NSMutableAttributedString
{
    func replace(target:String, with replacement:String, attributes:[String:NSObject]?)
    {
        var text = self.string
        var error:NSError?
        var regex = NSRegularExpression(pattern:target, options:.IgnoreMetacharacters, error:nil)
        var range = NSMakeRange(0, count(text))
        regex?.enumerateMatchesInString(text, options:nil, range: range, usingBlock: {
            (result:NSTextCheckingResult!, flags:NSMatchingFlags, stop:UnsafeMutablePointer<ObjCBool>) -> Void in
            let subStringRange = result.rangeAtIndex(0)
            let attributedString = NSAttributedString(string:replacement, attributes:attributes)
            self.replaceCharactersInRange(subStringRange, withAttributedString:attributedString)
        })
    }
}