编辑代码

func shuffleStudents(dict dictStudents : Dictionary<Int,String>) -> (num:Int?,name:String?)?
{
    if dictStudents.isEmpty
    {
        return nil
    }
    else{
        var arrayNumbers = [Int](dictStudents.keys)
        arrayNumbers.shuffle()
        
        let num = arrayNumbers[0]

        return (num,dictStudents[num])
        }
    
}

var students : [Int:String] = [:]
students[2020967017] = "邹徐陈"
students[2020967018] = "刘辉"
students[2020967019] = "胡鑫玉"
students[2020967020] = "吴长豪"
students[2020967021] = "薛传勇"




if shuffleStudents(dict : students) == nil{
    print("nil")
}
else{
    if let t = shuffleStudents(dict : students){
        print("请学号:\(t.num!)  姓名:\(t.name!)同学回答问题!")
    }
}