我想创建一个方法的协议，它接受通用输入并返回一个通用值。
这是我试过迄今为止，但它会产生语法错误。
Use of undeclared identifier T.
我究竟做错了什么？
protocol ApiMapperProtocol {
func MapFromSource(T) -> U
}
class UserMapper: NSObject,ApiMapperProtocol {
func MapFromSource(data: NSDictionary) -> UserModel {
var user = UserModel() as UserModel
var accountsData:NSArray = data["Accounts"] as NSArray
return user
}
}
对于协议有点不同。看看“关联类型”
in Apple’s documentation。
这是你在你的例子中使用它
protocol ApiMapperProtocol {
associatedtype T
associatedtype U
func MapFromSource(T) -> U
}
class UserMapper: NSObject,ApiMapperProtocol {
typealias T = NSDictionary
typealias U = UserModel
func MapFromSource(data:NSDictionary) -> UserModel {
var user = UserModel()
var accountsData:NSArray = data["Accounts"] as NSArray
// For Swift 1.2,you need this line instead
// var accountsData:NSArray = data["Accounts"] as! NSArray
return user
}
}
