Subclass type as function parameter

Question

I have an array of objects. The array contains different subclasses.

class MainClass {
}

class SubClass1:  MainClass{
}

class SubClass2:  MainClass{
}

var arrayOfObjects = [SubClass1(), SubClass2(), SubClass1()]

I want to include a function that removes all objects that are a specific subclass type.

arrayOfObjects = arrayOfObjects.compactMap { $0 as? Subclass1 }

How can I use the subclass type as function parameter?

func removeObjectsOf(type: //??) {
arrayOfObjects = arrayOfObjects.compactMap { $0 as? type }
}

Joakim Danielson · Accepted Answer · 2020-09-08T14:32:31.993

3

You can filter using type(of:)

let filtered = arrayOfObjects.filter { type(of: $0) == SubClass1.self }

or if you want to write it as a function

func filter(_ array: [MainClass], with classType: MainClass.Type) -> [MainClass] {
    array.filter { type(of: $0) == classType }
}

filter(arrayOfObjects, with: SubClass1.self)

edited Sep 08 '20 at 14:32

answered Sep 08 '20 at 14:27

Joakim Danielson

43,251
5
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score 1 · Answer 2 · answered Sep 08 '20 at 14:28

1

You can pass this kind of type as a generic type parameter:

func removeObjectsOf<T: MainClass>(type: T.Type) {
    arrayOfObjects = arrayOfObjects.compactMap { $0 as? T }
}

answered Sep 08 '20 at 14:28

Rob Napier

286,113
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Subclass type as function parameter

2 Answers2