Swift 字典 Dictionary基本用法

import UIKit
/*
字典的介绍
1.字典允许按照某个键访问元素
2.字典是由两部分组成, 一个键(key)集合, 一个是值(value)集合
3.键集合是不能有重复的元素, 值集合可以有重复的元素, 键和值是成对出现的
4.Swift 字典类型是Dictionary 也是一个泛型集合
5.字典分为可变字典和不可变字典
let 修饰不可变字典 var修饰可变字典
*/
//1.定义字典
//1>定义不可变字典
//OC @{@"name":@"summer",@"age":@18}
//系统会自动判断后面[]中存放的键值对,还是一个一个元素
let dict = ["name" : "summer", "age" : 18, "height" : 1.88] as [String : Any]
//2>定义可变字典
//var mutableDict = Dictionary<String, NSObject>() //方式一
//AnyObject: 一般指定类型 NSObject: 一般用于创建对象
//var mutableDict = [String : NSObject]() //方式二
var mutableDict = [String : AnyObject]() //常用方式三
//2.对可变字典的基本操作(增删改查)
//2.1> 添加元素
mutableDict["name"] = "summer" as AnyObject?
mutableDict["age"] = 18 as AnyObject?
mutableDict["height"] = 1.88 as AnyObject?
mutableDict["weight"] = 60 as AnyObject?
mutableDict
//2.2> 删除元素
mutableDict.removeValue(forKey: "age")
mutableDict
//2.3>修改元素
// 区别:如果字典中已经有了对应的key, 那么会直接修改原来key中保存的value
// 如果字典中没有对应的key, 那么添加对应的key/value
mutableDict["name"] = "sun" as AnyObject?
mutableDict
mutableDict ["sex"] = "女" as AnyObject?
mutableDict
//2.4> 获取某一个元素
mutableDict["sex"]
//3.遍历字典
//3.1>遍历字典中所有的key
for key in mutableDict.keys{
print(key)
}
//3.2>遍历字典中所以的值
for value in mutableDict.values{
print(value)
}
//3.3>遍历所有的键值对
for (key, value) in mutableDict{
print(key)
print(value)
}
//4.字典的合并
//即使类型一致也不能相加进行合并
//let dict1 = ["name":"summer", "age" : 18] as [String : Any]
//let dict2 = ["sex" : "男", "phoneNumber" : "+86 0393"] as [String : Any]
//
//let resultDict = dict1 + dict2 //写法是错误的
//如果必须合并那么只能
var dict1 = ["name":"summer", "age" : 18] as [String : Any]
let dict2 = ["sex" : "男", "phoneNumber" : "+86 0393"] as [String : Any]
for (key, value) in dict2{
dict1[key] = value as AnyObject?
}
dict1

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Swift 字典 Dictionary基本用法

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