Coreplot Animation of a sequence of plots - core-plot

Question

I have a number of plots, which depict (x,y) data at different time intervals, and wish to plot them in a sequence one after the other(like a gif file). My approach was generate all the plots, use a Timer.scheduledTimer and initially hide all plots, unhiding current plot and hiding previous plot at each fired schedule. The time between each plot hiding/unhiding shows a blank graph for more time than the plots are shown. Each plot has 32x32 data points. How can I speed this up, so I never see a blank graph? Another approach was to fade out one plot, whilst introducing the next, but I see the same effect.
#objc func tapAnimationButton(_ sender: Any) {
isAnimating = !isAnimating
plotSpacesUserInteraction = !plotSpacesUserInteraction
if let _animationButton = animationButton {
_animationButton.isSelected = isAnimating
previousAnimatedPlot = nil
if isAnimating {
animationCounter = 0
for i in 0..<plotDetails.count {
// fieldsplots[i].isHidden = true
fieldsplots[i].opacity = 0.0
}
animationTimer = Timer.scheduledTimer(timeInterval: 0.5, target: self, selector: #selector(animateGraph(_:)), userInfo: nil, repeats: true)
if let _animationTimer = animationTimer {
animateGraph(_animationTimer)
}
}
else {
animationTimer?.invalidate()
animationTimer = nil
}
}
}
#objc func animateGraph(_ timer: Timer) {
if animationSeconds > 120.0 {
timer.invalidate()
self.animationTimer = nil
animationSeconds = 0.0
animationCounter = 0
previousAnimatedPlot = nil
}
else {
if let currentAnimatedPlot = self.graph.plot(at: animationCounter) {
// previousAnimatedPlot?.isHidden = true
// currentAnimatedPlot.isHidden = false
previousAnimatedPlot?.opacity = 1.0
let fadeOutAnimation = CABasicAnimation(keyPath: "opacity")
fadeOutAnimation.duration = 0.1
fadeOutAnimation.isRemovedOnCompletion = false
fadeOutAnimation.fillMode = CAMediaTimingFillMode.forwards
fadeOutAnimation.toValue = Float(0.0)
previousAnimatedPlot?.add(fadeOutAnimation, forKey: "animateOpacity")
currentAnimatedPlot.opacity = 0.0
let fadeInAnimation = CABasicAnimation(keyPath: "opacity")
fadeInAnimation.duration = 0.1
fadeInAnimation.isRemovedOnCompletion = false
fadeInAnimation.fillMode = CAMediaTimingFillMode.forwards
fadeInAnimation.toValue = Float(1.0)
currentAnimatedPlot.add(fadeInAnimation, forKey: "animateOpacity")
previousAnimatedPlot = currentAnimatedPlot
}
animationSeconds += 0.5
animationCounter += 1;
if animationCounter >= plotDetails.count {
animationCounter = 0
}
}
}

Answer 1

The fade in/out method actually works...not sure how I missed that.

Answer 2

As an add-on to answer, in order to produce a gif image one needs to hide/unhide the plots in sequence
for currentPlot in self.graph.allPlots() {
currentPlot.isHidden = true
}
var images: [UIImage] = []
var previousPlot: CPTPlot?
for currentPlot in self.graph.allPlots() {
if let _previousPlot = previousPlot {
_previousPlot.isHidden = true
}
currentPlot.isHidden = false
if let image = graph.imageOfLayer() {
images.append(image)
}
previousPlot = currentPlot
}
for currentPlot in self.graph.allPlots() {
currentPlot.isHidden = false
}
if images.count > 2 {
TwoDPlot_Utilities.GIFExport(with: images, plot: thisplot, plotIndex: plotIndex, frameDelay: 0.5)
}