CALayer as SubLayer Not Visible - ios4

Question

I am trying to built an animated circle which would be drawn clockwise until it becomes complete circle as illustrated in iPhone Core Animation - Drawing a Circle
Problem is that CALayer object is not added or build. I tested and saw that it is not accessing my drawInContext:CGContextRef and animatingArc methods.
What so far I have done is:
In AnimateArc.h
#interface AnimateArc : CALayer {
CAShapeLayer *circle;
}
-(void) animatingArc;
#end
In AnimateArc.m
-(void) drawInContext:(CGContextRef)ctx
{
CGFloat radius = 50.0;
circle = [CAShapeLayer layer];
//make a circular shape
circle.path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0.0, 0.0, 2 * radius, 2 * radius) cornerRadius:radius].CGPath;
CGPoint centerPoint = CGPointMake(CGRectGetWidth(self.bounds)/2, CGRectGetHeight(self.bounds)/2);
//center the shape in self.view
circle.position = centerPoint;
//configure appearence of circle
circle.fillColor = [UIColor clearColor].CGColor;
circle.strokeColor = [UIColor blackColor].CGColor;
circle.lineWidth = 5;
/*CGPointMake((self.contentsCenter.size.width), (self.contentsCenter.size.height));*/
//path the circle
CGContextAddArc(ctx, centerPoint.x, centerPoint.y, radius, 0.0, 2 * M_PI, 0);
CGContextClosePath(ctx);
//fill it
CGContextSetFillColorWithColor(ctx, [UIColor redColor].CGColor);
CGContextFillPath(ctx); }
///////////////////////////////////////////////////////////////////////
-(void) animatingArc
{
CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:#"arcEnd"];
anim.duration = 20.0; //animate over 20 seconds
anim.repeatCount = 1.0; //animate only once
anim.removedOnCompletion = NO; //Reamin there after completion
//animate from start to end
anim.fromValue = [NSNumber numberWithFloat:50.0f];
anim.toValue = [NSNumber numberWithFloat:150.0f];
//experiment with timing to get appearence to look the way you want
anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
//add animation to circle
[circle addAnimation:anim forKey:#"animatingArc"];
}
/////////////////////
//needed since key not part of animatable properties
+(BOOL) needsDisplayForKey:(NSString *)key
{
if([key isEqualToString:#"arcEnd"])
return YES;
else
return [super needsDisplayForKey:key];
}
//ensure custom properties copied to presentation layer
-(id) initWithLayer:(id)layer
{
if((self = [super initWithLayer:layer]))
{
if ([layer isKindOfClass:[AnimateArc class]])
{
AnimateArc *other = (AnimateArc *) layer;
[other setNeedsDisplay];
}
}
return self; }
And finally in my viewController,
- (void)viewDidLoad
{
[super viewDidLoad];
[self.view.layer addSublayer:AnimateArcObject];
[AnimateArcObject animatingArc];
}
Apology for bad formatting.... Please can someone tell me what am I doing wrong? I have also doubt that my code can crash at any place after accessing those two functions since I am novice about Core Animation and haven't got any idea that I am in right direction or not.
Any help will be appreciated. Thanks.

Answer 1

From my painful experience with CoreAnimation, you must always set the bounds property of any CALayer you instantiate.
So, you're layer is not showing because you are missing something like:
layer.bounds = CGRectMake(0, 0, width, height);
you should place this as soon as you instantiate the layer, and make it a habit to do so, so you don't fall into it again.
As for your code crashing, sorry. It's too distributed and I am not sure how it's linked together, so I can't help you there.

Answer 2

After little searching, I thought that I am going in wrong direction. So I deleted this AnimateArc file and added new one which is inheriting from UIViewController.
Then in viewDidLoad Method, I wrote the code from this link to create circle and animations using path.
In parent view controller, I added AnimatedArc ViewController's subview. Now its working perfectly :)