Use of undeclared type 'T' when declared array of any type in Swift

Question

I'm trying to declare a property with an array of any type T. But I'm getting compiler error - Use of undeclared type 'T'. Below is the class that I created with 2 properties.

class Product {
 var productName: String;
 var items: Array<T>
}

Please let me know how to declare an array of any type using Generics in Swift. I've tried the below options:

{
var items: Array<T>;
var items = Array<T>();
var items = [T]();
}

Answer 1

You have to define the generic type in the class declaration:

class Product<T> {
    var productName: String;
    var items: Array<T>
}

Of course, since the class has uninitialized non optional variables, you have to either initialize them inline:

class Product<T> {
    var productName: String = ""
    var items: Array<T> = Array<T>()
}

make them optionals:

class Product<T> {
    var productName: String?
    var items: Array<T>?
}

define an initializer:

class Product<T> {
    var productName: String
    var items: Array<T>

    init(productName: String, items: Array<T>) {
        self.productName = productName
        self.items = items
    }
}

or any combination of them.

Note that the trailing semicolon is not required in swift, unless you put more than one statement in the same line