Change color of specific words in String

Question

I'm trying to change the color of specific words which start with a @ however I keep getting an error in the below code.

From what I can see it seem to be something with the range variable.

I get the following error:

cannot invoke 'addAttribute' with an argument list of type (String, value: UIColor, range Range?)

Code:

var messageMutableString = NSMutableAttributedString(string: message, attributes: [NSFontAttributeName:UIFont(name: "PT Sans", size: 13.0)!])

var words = message.componentsSeparatedByString(" ")

for word in words {
    if word.hasPrefix("@") {
        var range = message.rangeOfString(word)
        messageMutableString.addAttribute(NSForegroundColorAttributeName, value: UIColor(rgba: "#B52519"), range: range)
    }
}

Answer 1

Rather than split the string into components, I'd use a regular expression search to find the ranges of the strings beginning with @ and then apply the colour. Below is a working example:

extension String {

    public func getMatches(regex: String, options: NSStringCompareOptions?) -> [Range<String.Index>] {
        var arr = [Range<String.Index>]()
        var rang = Range(start: self.startIndex, end: self.endIndex)
        var foundRange:Range<String.Index>?

        do
        {
            foundRange = self.rangeOfString(regex, options: options ?? nil, range: rang, locale: nil)

            if let a = foundRange {
                arr.append(a)
                rang.startIndex = foundRange!.endIndex
            }
        }
            while foundRange != nil
        return  arr
    }

}


let message = "hello @you how are @you today?"
let matches = message.getMatches("@[^ ]{1,}", options: NSStringCompareOptions.RegularExpressionSearch)
let messageMutableString = NSMutableAttributedString(string: message, attributes: [NSFontAttributeName:UIFont(name: "Helvetica", size: 13.0)!])
for m in matches {
            messageMutableString.addAttribute(NSForegroundColorAttributeName, value: UIColor.redColor(), range: NSRange(location:distance(message.startIndex,m.startIndex),length:distance(m.startIndex,m.endIndex)))

}
messageMutableString // string with added attributes

The range issue is resolved in the following: NSRange(location:distance(message.startIndex,m.startIndex),length:distance(m.startIndex,m.endIndex)). Range and NSRange are not interchangeable, you must fulfil the requirement for one or the other. Using distance() you can retrieve the required Int values to instantiate an NSRange.