Recently I have been working on a project for my kids. Of course since it was a new project I decided to do it in the newest version of Swift. I wanted to make some simple games that could help my young ones learn.

I love playgrounds and all that they enable us to do. I came across this project that [@uraimo][uraimo] which has a running list of [Awesome Swift Playgrounds][Awesome-Swift-Playgrounds]. There is one for spriteKit, which I really wanted to make a game with but of course it was written in Swift 2.2 I was not about to let that hold me back so I went ahead and started trying to convert it to Swift 3. I went through all the changes that Xcode suggested and finally made it to a point where I had no errors. The issue was that the example did not perform the way it did previously. After going back and converting each function 1 by 1. I determined the function that was not being called.

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func didBeginContact(contact: SKPhysicsContact) {
        // Executed if the ball makes contact with the block.
        if contact.bodyA.categoryBitMask == CategoryBitMask.Ball && contact.bodyB.categoryBitMask == CategoryBitMask.Block {
            let block = contact.bodyB.node as! SKSpriteNode
            // Turn the block gray if it hasn't been hit yet.
            if block.name == "Block" {
                block.color = SKColor.darkGray
                block.name = "HalfBlock"
            }
            // Remove the block from the scene if it has already been hit.
            else {
                block.removeFromParent()
            }
        }
    }

Then the next step was to figure out what I am missing but when I would try and find something it was already outdated. Even Apple’s documentation was for objectiveC. Then it hit me that this function was not that swifty which is what allot of the changes for Swift 3 were all about. There is to much redundancy func didBeginContact(contact: SKPhysicsContact) { and therein lies the solution. See Xcode suggested to add the perimeter contact: and technically the method is valid so no errors were thrown. But this method is key for detecting collision between two objects and is the method that conforms to SKPhysicsContactDelegate. So since swift is aiming to be super readable if you take out the brackets it should read like a sentence of sorts. “did Begin Contact contact SKPhysicsContact” is a super redundant sentence in my book. Take out the first contact and all is well. I don’t know why Xcode did not remove it when it added the parameter label like it does in many other instances but that is neither here nor there.

So I corrected my mistake and everything works just as it should. Corrected Code :

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func didBegin(_ contact: SKPhysicsContact) {
        // Executed if the ball makes contact with the block.
        if contact.bodyA.categoryBitMask == CategoryBitMask.Ball && contact.bodyB.categoryBitMask == CategoryBitMask.Block {
            let block = contact.bodyB.node as! SKSpriteNode

            // Turn the block gray if it hasn't been hit yet.
            if block.name == "Block" {
                block.color = SKColor.darkGray
                block.name = "HalfBlock"
            }
            else {
                block.removeFromParent()
            }
        }
    }

Conclusion: When updating for Swift 3 don’t trust XCode (She will lie to you). Make sure you understand what is going on with the code and check your syntax. Allot changed but I think allot has really improved with the changes.

Now go out there and explore, change variables and learn about SpriteKit more, if you would like to check out the playground you can get the updated Swift 3 version here