swift的泛型也是使用<>的形式

函数、方法、类、枚举、结构体都可以使用泛型

func genericFunc<Item>(repeatItem item:Item,numberOfLoop:Int)->[Item] {
    var result = [Item]()
    for _ in 0..<numberOfLoop {
        result.append(item)
    }
    return result
}
var result1 = genericFunc(repeatItem: "LMC",numberOfLoop: 5)
print(result1)
var result2 = genericFunc(repeatItem: 1,numberOfLoop: 5)
print(result2)
var date = Date.init(timeInterval: 0,since: Date())
var result3 = genericFunc(repeatItem: date,numberOfLoop: 5)
print(result3)

enum EnumGeneric<Wrapped> {
    case success
    case failer(Wrapped)
}
var generic:EnumGeneric<String> = .success
generic = .failer("Hello")

在我们的方法体开始的前面 我们可以使用where 对参数做出一些约束 比如必须是实现了某一个协议 具有一个特定的父类

func genericWhere<T1,T2>(t1:T1,t2:T2)->Void where T1:ProtocolForGeneric,T2:SuperClassForGeneric{
    print(t1.discription)
    print(t2.discription)
}

完整的写上代码

protocol ProtocolForGeneric {
    var discription:String{ get }
    func hello()
}
class SuperClassForGeneric {
    var discription = "SuperClass"
    func hello() {
    }
}
func genericWhere<T1,T2:SuperClassForGeneric{
    print(t1.discription)
    print(t2.discription)
}
class SubClassForGeneric:SuperClassForGeneric {
    override init() {
        super.init()
        self.discription = "SubClassDiscription"
    }
    override func hello() {
    }
}
class ClassForGeneric: ProtocolForGeneric {
    var discription: String = "ProtocolDiscription"
    func hello() {
    }
}
genericWhere(t1: ClassForGeneric.init(),t2: SubClassForGeneric.init())