Swift 使用NumberFormatter为数字前补0

struct ScoreStruct {

    var home: Int
    var guest: Int
    let scoreFormatter: NumberFormatter

    init(home: Int, guest: Int) {
        self.home = home
        self.guest = guest
        scoreFormatter = NumberFormatter()
        scoreFormatter.minimumIntegerDigits = 2
    }
    
    var pretty: String {
        let h = scoreFormatter.string(from: home as NSNumber)!
        let g = scoreFormatter.string(from: guest as NSNumber)!
        return "\(h) – \(g)"
    }
}