1、Dictionary<Key, Value> 或者 [Key:Value]
2、特性
    a.字典是一種存儲多個相同類型的值的容器;
 b.每個值（value）都關(guān)聯(lián)唯一的鍵（key);
    c.字典中的數(shù)據(jù)項(xiàng)并沒有具體順序;   

1.創(chuàng)建

var tempDic : Dictionary<Int, String>
var tempDic1 = [Int: String]()

//用字典字面量創(chuàng)建字典
var airports: [String: String] = ["key1": "1", "key2": "2"]
var airports1 = ["key1": "1", "key2": "2"]

2、長度

var tempDic1 :[String: String] = ["key1": "1", "key2": "2", "key3": "3"]
print(tempDic1.count)  //3

3.是否為空

var tempDic1 :[String: String] = ["key1": "1", "key2": "2", "key3": "3"]
if !tempDic1.isEmpty {
    print("數(shù)組不為空")
}

4.增

var tempDic1 :[String: String] = ["key1": "1", "key2": "2", "key3": "3"]
tempDic1["key4"] = "4"
print(tempDic1)
//["key2": "2", "key3": "3", "key4": "4", "key1": "1"]

5.刪

var tempDic1 :[String: String] = ["key1": "1", "key2": "2", "key3": "3"]

tempDic1.removeValue(forKey: "key1")
print(tempDic1) //["key2": "2", "key3": "3"]

6.改

var tempDic1 :[String: String] = ["key1": "1", "key2": "2", "key3": "3"]
tempDic1["key1"] = "a"
print(tempDic1)  //["key2": "2", "key3": "3", "key1": "a"]

//updateValue 返回更新值之前的原值； 可選類型
var element1 :String? = tempDic1.updateValue("1", forKey: "key1")
print(element1)  // Optional("a")

7.字典遍歷

var tempDic1 :[String: String] = ["key2": "2", "key3": "3"]
for(key,value) in tempDic1{
    print("\(key) : \(value)")
}
//key2 : 2
//key3 : 3

//遍歷keys
for key in tempDic1.keys{
    print(key)
}
//key2
//key3

//遍歷values
for value in tempDic1.values{
    print(value)
}
//2
//3

8.某個字典的鍵值合構(gòu)型一個數(shù)組

var tempDic1 :[String: String] = ["key2": "2", "key3": "3"]
let keysArr = [String](tempDic1.keys)
print(keysArr)  //["key2", "key3"]

9.keys 或 values排序

print(tempDic1.keys.sorted())