Swift5 隨機數字母和數字混合

//隨機數字母和數字
    func getRandomStringWithNum(num:Int) -> String {
        var string = ""
        var i = 0
        while i<num {
            i+=1
            let number = arc4random() % 36
            if number < 10{
                let figure = arc4random() % 10;
                let tempString = String(figure)
                string = string + tempString
            } else {
                let figure = (arc4random() % 26) + 97;
                let character = Character(UnicodeScalar(figure)!)
                let tempString = String(character)
                string = string + tempString
            }
        }
        return string
    }

8位隨機數

let temp = getRandomStringWithNum(num: 8)