编辑代码

// func x(num1:inout Int , num2:inout Int){
//     var tmp:Int
//     tmp = num1
//     num1 = num2
//     num2 = tmp
// }
// var num11:Int = 100, num22:Int = 150
// print("前num1=\(num11),num2=\(num22)")
// x(num1:&num11,num2:&num22)
// print("后num1=\(num11),num2=\(num22)") 
var cityName:[String] = ["wuhan","beijing","shanghai","guangzhou"]
var citySorted = cityName.sorted(by: {
    (s1:String,s2:String) -> Bool in
        return s1 < s2
})