animate

animate

func animate(duration: TimeInterval, delay: TimeInterval) {
    UIView.animate(withDuration: 0.5, delay: 0, options: [.curveEaseOut], animations: {
        self.tree0.alpha = 1.0
        self.city.alpha = 1.0
        self.city2.alpha = 1.0
        self.manImage.alpha = 1.0
        }, completion: nil)
    
    // tree must disappear off the screen, so -50
    let treeAnimation = CABasicAnimation(keyPath: "position.x")
    treeAnimation.duration = duration
    let treeMid: Double = Double(self.city.frame.size.width)
    treeAnimation.fromValue = NSNumber(value: treeMid)
    treeAnimation.toValue = NSNumber(value: -50 )
    treeAnimation.repeatCount = .infinity
    self.tree0.layer.add(treeAnimation, forKey: "basic")
    
    let firstCityAnimation = CABasicAnimation(keyPath: "position.x")
    firstCityAnimation.duration = duration
    firstCityAnimation.fromValue = NSNumber(value: 0.0)
    firstCityAnimation.toValue = NSNumber(value: -1 * Int(self.city.frame.size.width))
    firstCityAnimation.repeatCount = .infinity
    self.city.layer.add(firstCityAnimation, forKey: "basic")

    let secondCityAnimation = CABasicAnimation(keyPath: "position.x")
    secondCityAnimation.duration = duration
    secondCityAnimation.fromValue = NSNumber(value: Int(self.city.frame.size.width) )
    secondCityAnimation.toValue = NSNumber(value: 0 )
    secondCityAnimation.repeatCount = .infinity
    self.city2.layer.add(secondCityAnimation, forKey: "basic")
}