直接上程式碼，給你個眼神，自己領悟！

 1 //Set排序
 2 let stringSet1 = Set(["car", "boat", "bike", "toy"])
 3 let stringArray1 = stringSet1.sorted()
 4 print(stringArray1)
 5 // will print ["bike", "boat", "car", "toy"]
 6 
 7 //Set去除元素第一位不為b字母的元素
 8 let stringSet2 = Set(arrayLiteral: "car", "boat", "car", "bike", "
 
toy") 
 9 let stringArray2 = stringSet2.filter { $0.characters.first != "b" }
10 print(stringArray2)
11 // may print ["car", "toy"]
12 
13 //Set<Int>轉換為[String]
14 let intSet3 = Set([1, 3, 5, 2]) 
15 //方法一：flatMap
16 let stringArray3 = intSet3.flatMap { String($0) }
17 print(stringArray3)
18 //
 
方法二：Array
19 let stringArray4 = Array(intSet3)
20 print(stringArray4)
21 // may print ["5", "2", "3", "1"]
22 
23 //Set<Int>轉換為[Int]
24 let intSet5 = Set([1, 3, 5, 2])
25 let intArray5 = intSet5.map { $0 }
26 print(intArray5)
27 // may print [5, 2, 3, 1]