Checking if object is not of type in swift

Question

I need to check if an object is not of a certain type. I know in Kotlin it's possible to check if a type is not by using !is. I was wondering if there was an equivalent in Swift, or a workaround I could use if it's not possible?

Example in Kotlin:

Assume animals is an interface of different animals and there are classes that implement it such as Cat, Dog, Horse, Spider, etc:

var animals = listOf<Animals>(Horse(), Cat(), Dog(), Spider())
var chosenAnimals = animals.filter { it !is Spider }

Answer 1

There is no equivalent in Swift, but its counterpart is the is operator. You only need to negate the operator result.

var animals = listOf<Animals>(Horse(), Cat(), Dog(), Spider())
var chosenAnimals = animals.filter { !($0 is Spider) }

Or, as you're using a mutating collection (var), you could use removeAll(where:) to remove all Spider instances to solve your problem.

var animals = listOf<Animals>(Horse(), Cat(), Dog(), Spider())
animals.removeAll { $0 is Spider } // animals.removeAll(where: { $0 is Spider })
print("Animals: \(animals)") // should not contain Spider instances

Answer 2

Or, you can create your own isNot function, like this:

extension Animal {
    func isNot<T: Animal>(_ type: T.Type) -> Bool {
        return !(self is T)
    }
}

print(Horse().isNot(Fish.self)) // prints true
print(Horse().isNot(Horse.self)) // prints false

Answer 3

Using swift syntax this is one way to do this

let animals: [Animals] = [Horse(), Cat(), Dog(), Spider()]
var chosenAnimals = animals.filter { type(of: $0) != Spider.self }

alternatively

var chosenAnimals = animals.filter { !($0 is Spider) }

Answer 4

you can use this:

var chosenAnimals = animals.filter({!($0 is Spider)})

Answer 5

Here's a working sample in Swift:

protocol Animal { }

class Horse : Animal { }
class Cat : Animal { }
class Dog : Animal { }
class Spider : Animal { }

let animals:[Animal] = [Horse(), Cat(), Dog(), Spider()]
let chosen = animals.filter { !($0 is Spider) }

Fill in your protocols/classes however you like :)