roman numeral to int in swift

main.swift
extension String {
    func romanNumeralToInt() -> Int {
        let romanDict = ["I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000]
        var result = 0
        
        for i in 0..<count {
            let current = romanDict[String(self[index(startIndex, offsetBy: i)])] ?? 0
            let next = (i+1 < count) ? romanDict[String(self[index(startIndex, offsetBy: i+1)])] ?? 0 : 0
            
            if current < next {
                result -= current
            } else {
                result += current
            }
        }
        
        return result
    }
}
598 chars
20 lines

main.swift
let romanNumeral = "MCMXCIV"
let integerValue = romanNumeral.romanNumeralToInt() // 1994
89 chars
3 lines