How to replace alphanumeric values in string in iOS?

Question

I want to replace all alphanumeric characters except white spaces in a string in iOS. Any compact solution?

This is my recent approach:

var strIn = "apple banana mushroom"
let a = (strIn).componentsSeparatedByString(" ")

var strReturn: NSString
for str in a {

    let str3 = "".stringByPaddingToLength((str as NSString).length, withString: "*", startingAtIndex: 0)
    strReturn = strReturn.stringByAppendingString(str3)
}

expected result is: "****** ****** ********"

Answer 1

A simple version could be something like that:

let strIn = "apple banana mushroom"
let words = strIn.componentsSeparatedByString(" ")

var starred: [String] = []

for word in words {
    let stars = Array(count: word.characters.count, repeatedValue: "*").joinWithSeparator("")
    starred.append(stars)
}

let result = starred.joinWithSeparator(" ")

Result:

"***** ****** ********"

You can make it an extension for easier usage:

extension String {
    var stars:String {
        let words = self.componentsSeparatedByString(" ")
        var starred: [String] = []
        for word in words {
            let stars = Array(count: word.characters.count, repeatedValue: "*").joinWithSeparator("")
            starred.append(stars)
        }
        return starred.joinWithSeparator(" ")
    }
}

let starred = "apple banana mushroom".stars

You can also replace the loop with map and produce some kind of monster one-liner. It's efficient but not very readable, so use at your own discretion:

extension String {
    var stars:String {
        return self.componentsSeparatedByString(" ").map { Array(count: $0.characters.count, repeatedValue: "*").joinWithSeparator("") }.joinWithSeparator(" ")
    }
}

let starred = "apple banana mushroom".stars