swit 字典用法，增删改查、合并

import UIKit//1定义字典//1.1定义不可变字典,系统会自动判断[]里面存放的是键值对还是数组元素let dic1 = ["name":"zhengyanfeng" , "age":16 , "height":1.88] as [String : Any]//1.2定义可变字典var dic2 = [String : Any]()//2.1可变字典添加元素dic2["name"] = "zhengyanfeng"dic2["age"] = 18dic2["height"] = 1.88dic2["weight"] = 125//2.2删除元素dic2.removeValue(forKey: "name")//2.3修改元素dic2["age"] = 16//2.4获取字典中的某一个元素dic2["age"]//3遍历字典//3.1遍历字典中所有的keyfor key in dic2.keys {    PRint(key)}//3.2遍历字典中所有的值for value in dic2.values {    print(value)}//3.3遍历字典中所有的键值对for (key , value) in dic2 {    print(key)    print(value)}//3.4合并字典//即使字典类型一致，也不能相加合并var dic3 = ["name":"zhengyanfeng"]let dic4 = ["school":"qinghua"]for (key , value) in dic4 {    dic3[key] = value}dic3