CODEWITHSUNDEEP
iosswiftuser-interfacesprite-kit2d-games
Matthew Kaplan
Matthew Kaplan

Reputation: 119

How to run a function when a long press has ended swift sprite kit

I'm running a very simple code and I'm trying to detect when a long press has ended and then execute a function but I can't seem to figure out how to do so. I have looked at lots of resources online but I haven't been able to figure it out. I'm very new to coding in Swift so if the answer is simple I apologize in advance. Here's all the code:

import SpriteKit

class GameScene: SKScene {

    let char = SKSpriteNode(imageNamed: "flying character")

    override func didMove(to view: SKView) {
        setScene()
    }

    @objc func press() {
        physicsWorld.gravity = CGVector(dx: 0.1, dy: 1.5)
        if UILongPressGestureRecognizer.State.changed == .ended {
            print ("the gesture has ended")
        }
    }

    func setScene() {
        backgroundColor = UIColor(red: 255/255, green: 255/255, blue: 221/255, alpha: 1.0)
        char.size = CGSize(width: frame.size.width/5, height: frame.size.width/5)
        char.run(SKAction.rotate(byAngle: .pi*11/6, duration: 0.00001))
        char.position = CGPoint(x: frame.midX - 100, y: frame.midY + 150)
        addChild(char)
        char.physicsBody = SKPhysicsBody(circleOfRadius: char.size.width/2)
        char.physicsBody?.categoryBitMask = PhysicsCategories.charCategory
        physicsWorld.gravity = CGVector(dx: 0.1, dy: -1.5)
        char.physicsBody?.affectedByGravity = true
        view?.addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: #selector(press)))
    }
}

as you can see I'm just trying to execute the print command when the long press has ended.

Upvotes: 0

Views: 79

Answers (1)

Enzo Maruffa
Enzo Maruffa

Reputation: 46

First of all, a very important thing you might notice is that your problem is not related to SpriteKit itself! You are using a UILongPressGestureRecognizer, a class from UIKit! Apple Docs

Also, note that you are applying the gesture to the whole view. As I assume that this is a game with a character that flies, I imagine that this behaviour is the intended one.

I imagine that the problem you are facing is that you are not working with the UILongPressGestureRecognizer assigned to your view! Instead, you are accessing UILongPressGestureRecognizer class properties/methods. For more details you can browse this section of the Swift documentation

A quick solution to you problem is to change your press function from 

@objc func press() {
    physicsWorld.gravity = CGVector(dx: 0.1, dy: 1.5)
    if UILongPressGestureRecognizer.State.changed == .ended {
        print ("the gesture has ended")
    }
}

to

@objc func press(_ gestureRecognizer: UILongPressGestureRecognizer) {
    physicsWorld.gravity = CGVector(dx: 0.1, dy: 1.5)
    if gestureRecognizer.state == .ended {
        print ("the gesture has ended")
    }
}

and your setScene function from

view?.addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: #selector(press)))

to

view?.addGestureRecognizer(UILongPressGestureRecognizer(target: self, action: #selector(press:)))

More information here

SpriteKit handles touch events in a quite raw way, but it might give you a bit more control on how you want to respond to these events. As KnightOfDragon said, it's quite like reinventing the wheel.

If you want to take a look on how SpriteKit does it, see this example. It's quite short, but I hope it helps :)

Upvotes: 3

Related Questions