Alternative way to fade the background color into another color - sprite-kit

Question

in my touches began method i put this simple line of code which fades the background color to red.
runAction(SKAction.colorizeWithColor(SKColor.redColor(), colorBlendFactor: 1.0, duration: 1.0))
everything is working fine, but the problem is that the code doesn't do anything using ios 7. I was wondering if there is an alternative way to make the background fade into a different color, or if there's an ios 7 version of this code.

Answer 1

There are multiple ways to transition from one color to another. One of the most straightforward approaches is to linearly interpolate between the two colors by combining a progressively larger fraction of the starting color's RGB components with a progressively smaller fraction of the ending color's RBG components over time:
red = starting_red * (1.0 - fraction) + ending_red * fraction
green = starting_green * (1.0 - fraction) + ending_green* fraction
blue = starting_blue * (1.0 - fraction) + ending_blue * fraction
where fraction starts at 0 and ends at 1 in increments of
fraction += delta_time * step_size
One way to implement this approach is to add code to the didMoveToView method of GameScene. However, if your game contains multiple scenes, a better strategy is to extend SKAction to add a class method that creates a custom action, so it can be used by all scenes.
First, define a structure to store the starting and ending RGB color components. Add this outside of the definition of GameScene.
struct ColorComponents {
var red:CGFloat
var green:CGFloat
var blue:CGFloat
init(color:SKColor) {
self.init()
var alpha:CGFloat = 0
color.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
}
init() {
red = 0
green = 0
blue = 0
}
}
Then, extend SKAction by adding the following method that changes the background color to another color. Note that extensions must be defined outside of a class.
extension SKAction {
static func changeColor(startColor:SKColor, endColor:SKColor, duration:NSTimeInterval) -> SKAction {
// Extract and store starting and ending colors' RGB components
let start = ColorComponents(color: startColor)
let end = ColorComponents(color: endColor)
// Compute the step size
let stepSize = CGFloat(1/duration)
// Define a custom class to gradually change a scene's background color
let change = SKAction.customActionWithDuration(duration) {
node, time in
let fraction = time * stepSize
let red = start.red * (1.0 - fraction) + end.red * fraction
let green = start.green * (1.0 - fraction) + end.green * fraction
let blue = start.blue * (1.0 - fraction) + end.blue * fraction
if let scene = node as? SKScene {
scene.backgroundColor = SKColor(red: red, green: green, blue: blue, alpha: 1.0)
}
}
return change
}
}
Lastly, create and run an SKAction
runAction(SKAction.changeColor(backgroundColor, endColor: SKColor.blueColor(), duration: 5))
Add this to didMoveToView in your SKScene subclasses, such as GameScene.