How Do I Blur a Scene in SpriteKit?

Question

How would I add a gaussian blur to all nodes (there\'s no fixed number of nodes) in an SKScene in SpriteKit? A label will be added on top of the scene later, this will be m

Answer 1

Swift 3 Update: This is @Chuck Gaffney's answer updated for Swift 3. I know this question is tagged objective-c, but this page ranked 2nd in Google for "swift spritekit blur". I changed currentScene to self.

    func getBluredScreenshot() -> SKSpriteNode{

    //create the graphics context
    UIGraphicsBeginImageContextWithOptions(CGSize(width: self.view!.frame.size.width, height: self.view!.frame.size.height), true, 1)

    self.view!.drawHierarchy(in: self.view!.frame, afterScreenUpdates: true)

    // retrieve graphics context
    _ = UIGraphicsGetCurrentContext()

    // query image from it
    let image = UIGraphicsGetImageFromCurrentImageContext()

    // create Core Image context
    let ciContext = CIContext(options: nil)
    // create a CIImage, think of a CIImage as image data for processing, nothing is displayed or can be displayed at this point
    let coreImage = CIImage(image: image!)
    // pick the filter we want
    let filter = CIFilter(name: "CIGaussianBlur")
    // pass our image as input
    filter?.setValue(coreImage, forKey: kCIInputImageKey)

    //edit the amount of blur
    filter?.setValue(3, forKey: kCIInputRadiusKey)

    //retrieve the processed image
    let filteredImageData = filter?.value(forKey: kCIOutputImageKey) as! CIImage
    // return a Quartz image from the Core Image context
    let filteredImageRef = ciContext.createCGImage(filteredImageData, from: filteredImageData.extent)
    // final UIImage
    let filteredImage = UIImage(cgImage: filteredImageRef!)

    // create a texture, pass the UIImage
    let texture = SKTexture(image: filteredImage)
    // wrap it inside a sprite node
    let sprite = SKSpriteNode(texture:texture)

    // make image the position in the center
    sprite.position = CGPoint(x: self.frame.midX, y: self.frame.midY)

    let scale:CGFloat = UIScreen.main.scale

    sprite.size.width  *= scale

    sprite.size.height *= scale

    return sprite


}

func loadPauseBGScreen(){

    let duration = 1.0

    let pauseBG:SKSpriteNode = self.getBluredScreenshot()

    pauseBG.alpha = 0
    pauseBG.zPosition = self.zPosition + 1
    pauseBG.run(SKAction.fadeAlpha(to: 1, duration: duration))

    self.addChild(pauseBG)

}