Detect if an object is exactly a specific type and not a subclass of that type in swift

Question

In swift you can check if an object is of a specific type using something similar to the following

let object: AnyObject = someOtherObject
if object is SKNode {
   //is SKNode
}

In this case SKShapeNode and SKSpriteNode would also satisfy this condition as they subclass SKNode.

What is the standard way to detect if an object is of a specific type and not a subclass of that type?

Answer 1

You could fall back to Objective-C:

if (object as AnyObject).isMemberOfClass(SKNode) {
   //is SKNode
}

Answer 2

The Apple-approved way to do this in Swift 2.2 is:

if object.dynamicType === SKNode.self {
   // is node
}

and once this proposal is implemented (Swift 3.0), it will change to:

if object.Self === SKNode.self {
   // is node
}

Answer 3

This is not how the is operator works. If you do that, you'll get a compile error.

The is operator is used to check whether an object of a particular type is of a given sub-type. Using SKNode and SKShapeNode as examples, you'd use is to verify whether a object typed as SKNode is an SKShapeNode or an SKSpriteNode.

Paste this into a playground to get an idea of how it works:

let shape: SKNode = SKShapeNode()
let sprite: SKNode = SKSpriteNode()
let anotherShape = SKShapeNode()

if shape is SKShapeNode {
    println("is shape")
}

if sprite is SKSpriteNode {
    println("is sprite")
}

if shape is SKNode {
    //this raises a compile error, because the test is always true
}

if anotherShape is SKNode {
    //this raises a compile error, because SKNode is not a subtype of SKShapeNode
}

Answer 4

In swift 3:

if type(of: object) == SKNode.self {
   // is node
}