How to change colour of all numbers in a string in swift

Question

I am trying to change colour for all numbers present in a string in swift code.Example:

var mystring = \"abc 3423 opqrs 474598 lmno 343543\"
         


        

Answer 1

First, we need to find the ranges of number existed in the string. One way is to use regular expression

func findNumberRanges(string: String) -> [NSRange]{
    let nsString = string as NSString
    let regex = try? NSRegularExpression(pattern: "[0-9]+", options: [])
    let matches = regex?.matches(in: string, options: .withoutAnchoringBounds, range: NSMakeRange(0, nsString.length))
    return matches?.map{$0.range} ?? []
}

Then we can iterate through ranges of number to add the attribute, in this case to set red color.

func attributedNumberString(string: String, numberAttribute: [String: Any]) -> NSAttributedString{
    let ranges = findNumberRanges(string: string)

    let attributedString = NSMutableAttributedString(string: string)
    for range in ranges{
        attributedString.addAttributes(numberAttribute, range: range)
    }
    return attributedString
}

Here is how it is used:

let redColorAttribute = [ NSForegroundColorAttributeName: UIColor.red]
attributedNumberString(string: "6h40m", numberAttribute: redColorAttribute)