RemoveAtIndex crash from swift array

Question

I have an array of letters, and want to match the characters against the letters and then do something to that letter (in this case turn it yellow) and then remove that matched

Answer 1

So you have an array of Character(s):

let letters = Array("randomness")

An array of special Character(s)

let specials = Array("ness")

And you want to remove from letters, the specials right?

Here it is:

let set = Set(specials)
let filtered = letters.filter { !set.contains($0) }

filtered // ["r", "a", "d", "o", "m"]

Update

This version keep also consider the occurrences of a char

let letters = Array("randomness")
let specials = Array("ness")

var occurrencies = specials.reduce([Character:Int]()) { (var dict, char) in
    dict[char] = (dict[char] ?? 0) + 1
    return dict
}

let filtered = letters.filter {
    if let num = occurrencies[$0] where num > 0 {
        occurrencies[$0] = num - 1
        return false
    } else {
        return true
    }
}

filtered // ["r", "a", "d", "o", "m", "n"]