泛型
在程序设计中，要实现任意数据类型执行统一的一段操作，可以运用模版，对于整型、字符型、浮点型或者其他类型，均可以实现，这就叫泛型，可以重复利用。
编写泛型函数的步骤是：将涉及不同代码的部分用T表示。
struct Student {
var name = "name"
var height = 160.00
}
override func viewDidLoad() {
super.viewDidLoad()
var xiaoMing = Student()
var xiaoHong = Student()
xiaoMing.name = "xiaoHong"
xiaoHong.name = "xiaoMing"
xiaoMing.height = 172.5
xiaoHong.height = 168.5
print("交换之前：\n xiaoMing:\(xiaoMing)\n xiaoHong:\(xiaoHong)")
//名字搞错了，交换一下
exchange(objectA: &xiaoHong.name, objectB: &xiaoMing.name)
//身高也搞错了，交换一下
exchange(objectA: &xiaoHong.height, objectB: &xiaoMing.height)
print("交换之后：\n xiaoMing:\(xiaoMing)\n xiaoHong:\(xiaoHong)")
}
func exchange<T>(objectA:inout T,objectB:inout T) {
let temp = objectA
objectA = objectB
objectB = temp
}
inout关键字表示可以修改外部的变量值。
运行结果：
交换之前：
xiaoMing:Student(name: "xiaoHong", height: 172.5)
xiaoHong:Student(name: "xiaoMing", height: 168.5)
交换之后：
xiaoMing:Student(name: "xiaoMing", height: 168.5)
xiaoHong:Student(name: "xiaoHong", height: 172.5)
