传递 Codable 结构时无法推断通用参数“T”

Question

Please go through the code first for better understanding.

func getType<T: Decodable>(urlString: String, header: HTTPHeaders, completion: @escaping (T?) -> Void){

}

let networkManager = DataManager()

 networkManager.getType(urlString: kGetMyDayTaskDetails + strId, header: header) { (MyDayAndTaskDetails) in

}

Error:

Generic parameter 'T' could not be inferred

I am trying to pass the struct as parameter using Generics to use a common method for api calling. But not getting how to call correctly. Please guide.

Answer 1

Consider that the parameter in the closure is an instance , not a type. For example like

networkManager.getType(urlString: kGetMyDayTaskDetails + strId, 
                          header: header) { details in

}

To specify the generic type annotate it and according to the signature it must be optional

networkManager.getType(urlString: kGetMyDayTaskDetails + strId, 
                          header: header) { (details : MyDayAndTaskDetails?) in 

}