// before
    var japaneseChars : Set<String> {
        return Set(japaneseNumericalChars.keys)
    }

// after
    var japaneseChars : CharacterSet {
        return CharacterSet(charactersIn: japaneseNumericalChars.keys.joined())
    }

characterSetはSetとほぼ同じように使えるが、containsメソッドでStringを引数に使えないので、以下のようにrangeOfCharacter(from searchSet: CharacterSet) を使う

// before 
    func checkType(_ str : String) -> Int {
        
        switch str {
        case str where japaneseChars.contains(str):
            return 0
        case str where japaneseExpChars.contains(str):
            return 1
        default:
            return 2
        }
    }

// after 
    func checkType(_ str : String) -> Int {
        
        switch str {
        case str where str.rangeOfCharacter(from: japaneseChars) != nil:
            return 0
        case str where str.rangeOfCharacter(from: japaneseExpChars) != nil:
            return 1
        default:
            return 2
        }
    }

参考 :
rangeOfCharacter(from:) - NSString | Apple Developer Documentation
stackoverflow.com

2017-06-26

Stringのextensionにcomputed propertyをつくる

swift

before :

extension String {
    func numeralsToNumber() -> String {
        enum Chartype {
            case numerical
            case exp
            case normal
            
            init(_ number : Int) {
                switch number {
                case 0,1:
                    self = .numerical
//                case 1:
//                    self = .exp
                default:
                    self = .normal
                }
            }
        }
        
        let japaneseNumericalChars : [String : String] = [
            "〇": "0",
            "一": "1",
            "二": "2",
            "三": "3",
            "四": "4",
            "五": "5",
            "六": "6",
            "七": "7",
            "八": "8",
            "九": "9",
            ]
        let japaneseChars : Set = Set(japaneseNumericalChars.keys)

        let japaneseNumericalExpChars : [String : String] = [
            "十": "1",
            "百": "2",
            "千": "3",
            "万": "4",
            "億": "8",
            ]
        let japaneseExpChars : Set = Set(japaneseNumericalExpChars.keys)
        
        var splitedStr : [String] = []
        // 以下略

after :

extension String {
    var japaneseNumericalChars : [String : String] {
        return  [
            "〇": "0",
            "一": "1",
            "二": "2",
            "三": "3",
            "四": "4",
            "五": "5",
            "六": "6",
            "七": "7",
            "八": "8",
            "九": "9",
        ]
    }
    
    var japaneseChars : CharacterSet {
        return CharacterSet(charactersIn: japaneseNumericalChars.keys.joined())
    }
    
    private func convertCharToStr1To9(_ char : Character) -> String {
        return japaneseNumericalChars[char.description]!
    }
    
    var japaneseNumericalExpChars : [String : String] {
        return  [
            "十": "1",
            "百": "2",
            "千": "3",
            "万": "4",
            "億": "8",
        ]
    }
    
    var japaneseExpChars : CharacterSet {
        return CharacterSet(charactersIn: japaneseNumericalExpChars.keys.joined())
    }
    
    private func convertExpStrToNumStr(_ str : String) -> String {
        return japaneseNumericalChars[str]!
    }
    
    enum Chartype {
        case numerical
        case exp
        case normal
        
        init(_ number : Int) {
            switch number {
            case 0,1:
                self = .numerical
            default:
                self = .normal
            }
        }
    }
    
    func numeralsToNumber() -> String {
        
        var splitedStr : [String] = []
        // 以下略

computed propertyはletでできないとかdictionaryプロパティに直接アクセスできないから専用のメソッドを作ったりしないといけないとか色々あったけど大きな問題はなく実装できた。