1.基本使用
import UIKit
var a:Dictionary<String,String> = ["a":"A","b":"B","c":"C"]//初始化
print(a)
print(a["a"] ?? "unknow")//A。a["a"]可能不存在,这也是处理可选类型的一种方式(可以推广)
a["a"] = "hello"
print(a)
print(a.count)//打印长度
a.updateValue("Swift", forKey: "iOS")//将key“iOS”的value修改为“Swift”,如果key不存在会自动添加
print(a)
a.removeValue(forKey: "b")//根据关键字删除字典元素
print(a)
var b:[Int:String] = [1:"a",2:"b",3:"c"]//初始化。还可以使用类型推断
print(b)
2.过滤
import UIKit
var a:Dictionary<String,String> = ["a":"A","b":"B","c":"C"]//初始化
var b = a.filter({(key,value)->Bool in
if(key == "b"){
return false//删除key:“b”
}else{
return true
}
})
print(b)//["c": "C", "a": "A"]
3.字典的遍历
import UIKit
var a:Dictionary<String,String> = ["a":"A","b":"B","c":"C"]//初始化
for (a,b) in a{
print("key:"+a+"对应"+"value:"+b)
}