ios Sprite Kit screengrab?

Question

I am trying to get a screen grab of a view that has a SKScene in it. The technique I am using is:

UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, scale);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

This works great with normal UIViews, but for whatever reason it is ignoring all the sprites in the SKScene.

I'm not sure if this is a bug, or if Sprite Kit's rendering is separate from UIGraphics.

Question: How do I get a screen grab of an SKScene when the way that worked for UIViews seems to not work with Sprite Kit, or has anyone had success using UIGraphics context with Sprite Kit?

Answer 1

You almost have it, but the problem is as explained in the comment above. If you want to capture SKScene contents, try something like this instead:

UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, scale);
[self.view drawViewHierarchyInRect:self.bounds afterScreenUpdates:YES];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

The solution is to basically use the new method drawViewHierarchyInRect:afterScreenUpdates instead, which is the best we have for now; note, it's not exactly speedy, so doing this in realtime will not be pretty.

Answer 2

As a faster alternative, you can use the textureFromNode method on SKView, which returns an image of the view as an SKTexture. Simply pass the SKScene as the argument:

let texture = skView.textureFromNode(scene)

Or to capture part of the scene:

let texture = skView.textureFromNode(scene, crop: cropRect)

Answer 3

//1: get texture from "someNode"

let texture = skView.textureFromNode(someNode)

//2: get UIImage from the node texture

let image = UIImage(cgImage: texture!.cgImage())

Answer 4

A solution for Swift:

func getScreenshot(scene: SKScene, duration:TimeInterval = 0.0001, completion:((_ txt:SKTexture) -> Void)?) {
    let action = SKAction.run {
        let bounds = scene.view?.bounds
        var image = UIImage()
        UIGraphicsBeginImageContextWithOptions(bounds!.size, true, UIScreen.main.scale)
        scene.view?.drawHierarchy(in: bounds!, afterScreenUpdates: true)
        if let screenshot = UIGraphicsGetImageFromCurrentImageContext() {
            UIGraphicsEndImageContext()
            image = screenshot
        } else {
            assertionFailure("Unable to make a screenshot for the scene \(type(of:scene))")
        }
        completion!(SKTexture(image: image))
    }
    let wait = SKAction.wait(forDuration: duration)
    let seq = SKAction.sequence([wait,action])
    scene.run(seq,withKey:"getScreenshot")
}

Usage:

getScreenshot(scene: self, completion:{ (txt) -> Void in
            let thumbNode = SKSpriteNode(texture: txt, size:CGSize(width:300,height:224))
            // do whatever you want with your screenshot..
}