How to use generics as params?(Swift 2.0) - ios

Question

Code in playground is here
class ProductModel {
var productID : Int = 0
init(id:Int) {
productID = id
}
}
protocol GenericListProtocol {
typealias T = ProductModel
var list : [T] { get set }
var filteredlist : [T] { get set }
func setData(list : [T])
}
extension GenericListProtocol {
func setData(list: [T]) {
list.forEach { item in
guard let productItem = item as? ProductModel else {
return
}
print(productItem.productID)
}
}
}
class testProtocol {
class func myfunc<N:GenericListProtocol>(re:N){
var list : [ProductModel] = [ProductModel(id: 1),ProductModel(id: 2),ProductModel(id: 3),ProductModel(id: 4)]
re.setData(list)
}
}
But in the line re.setData(list)
get compile error:
Cannot convert value of type '[ProductModel]' to expected argument
type '[_]'.
My Question is How to use setData method in GenericListProtocol?
Anyone could help will be appreciated.

Answer 1

Moving the ProductModel type into the extension and removing the constraint from the generic protocol seems to work.
class ProductModel {
var productID : Int = 0
init(id:Int) {
productID = id
}
}
protocol GenericListProtocol {
typealias T
var list : [T] { get set }
var filteredlist : [T] { get set }
func setData(list : [T])
}
extension GenericListProtocol {
func setData(list: [ProductModel]) {
list.forEach { item in
print(item.productID)
}
}
}
class testProtocol {
class func myfunc<N:GenericListProtocol>(re:N) {
let list : [ProductModel] = [ProductModel(id: 1),ProductModel(id: 2),ProductModel(id: 3),ProductModel(id: 4)]
re.setData(list)
}
}

Answer 2

I found this question interesting and thought how best we could solve it in generic way.
protocol Product {
var productID : Int {get set}
}
class ProductModel: Product {
var productID : Int = 0
init(id:Int) {
productID = id
}
}
protocol GenericListProtocol {
typealias T : Product
var list : [T] { get set }
var filteredlist : [T] { get set }
}
extension GenericListProtocol {
func setData(list: [T]) {
list.forEach { item in
print(item.productID)
}
}
}
class GenericListProtocolClass : GenericListProtocol
{
typealias T = ProductModel
var intVal = 0
var list = [T]()
var filteredlist = [T]()
}
class testProtocol {
class func myfunc(re: GenericListProtocolClass){
let list : [ProductModel] = [ProductModel(id: 1),ProductModel(id: 2),ProductModel(id: 3),ProductModel(id: 4)]
re.setData(list)
}
}
let temp = GenericListProtocolClass()
testProtocol.myfunc(temp)
Appreciate your thought and suggestion if it can be improved further.