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
- }
- }
