Swift - class method which must be overridden by subclass

Question

Is there a standard way to make a \"pure virtual function\" in Swift, ie. one that must be overridden by every subclass, and which, if it is not, causes a c

Answer 1

You can use protocol vs assertion as suggested in answer here by drewag. However, example for the protocol is missing. I am covering here,

Protocol

protocol SomeProtocol {
    func someMethod()
}

class SomeClass: SomeProtocol {
    func someMethod() {}
}

Now every subclasses are required to implement the protocol which is checked in compile time. If SomeClass doesn't implement someMethod, you'll get this compile time error:

error: type 'SomeClass' does not conform to protocol 'SomeProtocol'

Note: this only works for the topmost class that implements the protocol. Any subclasses can blithely ignore the protocol requirements. – as commented by memmons

Assertion

class SuperClass {
    func someFunc() {
        fatalError("Must Override")
    }
}

class Subclass : SuperClass {
    override func someFunc() {
    }
}

However, assertion will work only in runtime.