[Swift] Clean code
\nclass Solution {\n    func longestPalindrome(_ words: [String]) -> Int {\n        var dict = Array(repeating: Array(repeating: 0, count:26), count:26)\n      
```\nclass Solution {\n    func longestPalindrome(_ words: [String]) -> Int {\n        var dict = Array(repeating: Array(repeating: 0, count:26), count:26)\n        var ans = 0\n        for w in words {\n            var arrWords = Array(w)\n            var a = Index(of: arrWords[0])\n            var b = Index(of: arrWords[1])\n            if dict[b][a] > 0 {\n                ans += 4\n                dict[b][a] -= 1\n            } else {\n                dict[a][b] += 1\n            }\n        }\n        for i in 0..<26 {\n            if dict[i][i] > 0 {\n                ans += 2\n                break\n            }\n        }\n        return ans\n    }\n    \n    func Index(of char: Character) -> Int {\n        return Int(char.asciiValue! - Character("a").asciiValue!)\n    }\n}\n```
['Swift']