add an animation to bar plot does not take effect visually - core-animation

Question

I am a newer to core plot. And recently I decide to add bar growth animation to my plot. so I followed the instruction searched here to implement the animation. Now I come up with the problem: the animation seemed not to take effect.The delegate: didStopAnimate:(BOOL) returns no matter how long I set the duration of the animation with flag false.
One more thing to state: in the graph view, I put a scrollview under the real graph hosting view. does that affect Core animation to work?
the plot appeared after a navigation from the table view to itself. here is some of my codes:
if ([plot_type isEqualToString:#"bar"]) {
CPTBarPlot *plot = [[CPTBarPlot alloc] init];
//id
plot.identifier = [d objectForKey:#"title"];
plot.title = [d objectForKey:#"title"];
plot.lineStyle = barLineStyle;
plot.barCornerRadius = 1.2;
//set color
CPTGradient *gradient = [CPTGradient gradientWithBeginningColor:[CPTColor colorWithCGColor:color_begin] endingColor:[CPTColor colorWithCGColor:color_end]];
gradient.angle = 90.0f;
CPTFill *fill = [CPTFill fillWithGradient:gradient];
plot.fill = fill;
//bar width
double width = [[d objectForKey:#"width"] doubleValue]==0.0?0.6:[[d objectForKey:#"width"] doubleValue];
plot.barWidth = CPTDecimalFromFloat(width);
plot.barsAreHorizontal = NO;
//need manually stacked
if (need_stack && !is_first) {
plot.barBasesVary = YES;
} else {
plot.barBasesVary = NO;
}
//data source
plot.dataSource = self;
//delegate
plot.delegate = self;
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:#"transform"];
[anim setDuration:2.0f];
anim.toValue = [NSNumber numberWithFloat:1];
anim.fromValue = [NSNumber numberWithFloat:0.0f];
anim.removedOnCompletion = NO;
anim.delegate = self;
anim.fillMode = kCAFillModeForwards;
[plot addAnimation:anim forKey:(NSString *)plot.identifier];
[graph addPlot:plot toPlotSpace:plotSpace];
}
Thanks for your helps in advance.

Answer 1

The transform property of a CALayer is CATransform3D struct, not a scalar value. You should wrap it using the NSValue method +valueWithCATransform3D:.