A simple function that returns true if two strings have the same exact characters -regardless of order- or false otherwise.

sameCharacters.swift

func sameCharacters(string stringOne: String, string stringTwo: String) -> Bool {
    let stringOneCharacters = stringOne.characters
    let stringTwoCharacters = stringTwo.characters
    
    // Early exit 1
    if stringOneCharacters.count != stringTwoCharacters.count {
        return false
    }
    
    var charMatched = false
    var matchedIndices = [Int](count: stringOneCharacters.count, repeatedValue: 0)
    
    for charOne in stringOneCharacters {
        for (i, charTwo) in stringTwoCharacters.enumerate() {
            if charOne == charTwo && matchedIndices[i] == 0 {
                charMatched = true
                matchedIndices[i] = 1
                break
            }
        }
        
        // Early exit 2
        if charMatched == false {
            return false
        }
        
        charMatched = false
    }
    
    return true
}

sameCharacters(string: "hello", string: "olelh") // returns true
sameCharacters(string: "URLER", string: "RULEG") // returns false