How do I animate the appearance of a bar chart in Core Plot?

Question

When first displaying a bar chart using Core Plot, I'd like the bars to grow upward until they reach their correct heights.

How would you create such an animation using this framework?

Answer 1

This is what I did:

1. In my viewDidLoad controller's method I created the CPTXYGraph:

   graph = [[CPTXYGraph alloc] initWithFrame:self.view.bounds];
   

2. I added animation to the empty graph:

   CAKeyframeAnimation *scale = [CAKeyframeAnimation animationWithKeyPath:@"transform"];
   

3. Then in animationDidStop delegate's method I added the plot data and animation to the graph:

   CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"transform.scale.y"];
   [anim setDuration:2.0f];
   
   anim.toValue = [NSNumber numberWithFloat:1.0f];
   anim.fromValue = [NSNumber numberWithFloat:0.0f];
   anim.removedOnCompletion = NO;
   anim.delegate = self;
   anim.fillMode = kCAFillModeForwards;
   
   gPlot.anchorPoint = CGPointMake(0.0, 0.0);
   
   [gPlot addAnimation:anim forKey:@"grow"];
   
   [graph addPlot:gPlot ];// IMPORTANT here I added the plot data to the graph :) .