Antialiasing on CAShapeLayers - objective-c

Question

I have a custom view for a loading indicator which is comprised of a number of CAShapeLayers which I perform various animations on to represent various states. In the init method I create a number of shape layers and add them as sublayers to the view's layer. The issue I'm having is the shapes that I'm drawing have very rough edges and don't seem to be antialiased. I've tried a number of things from similar answers on here but I can't seem to antialias the shapes. I've never had this problem before then drawing directly in drawRect.
Is there anything I'm missing or is there a better way to accomplish what I'm trying to do?
Update: Here's a comparison of how the shapes are being drawn:
On the left I'm drawing in layoutSubviews using this code:
CGFloat lineWidth = 2.5f;
CGFloat radius = (self.bounds.size.width - lineWidth)/2;
CGPoint center = CGPointMake(CGRectGetWidth(self.frame)/2, CGRectGetHeight(self.frame)/2);
CGFloat startAngle = - ((float)M_PI / 2);
CGFloat endAngle = (2 * (float)M_PI) + startAngle;
UIBezierPath *trackPath = [UIBezierPath bezierPathWithArcCenter:center
radius:radius
startAngle:startAngle
endAngle:endAngle
clockwise:YES];
self.trackLayer.path = trackPath.CGPath;
self.trackLayer.lineWidth = lineWidth;
On the right I'm calling a separate method from awakeFromNib:
-(void)awakeFromNib
{
....
self.trackLayer = [self trackShape]
[self.layer addSublayer:self.trackLayer];
}
-(CAShapeLayer*)trackShape
{
float start_angle = 2*M_PI*-M_PI_2;
float end_angle = 2*M_PI*1-M_PI_2;
float minSize = MIN(self.frame.size.width, self.frame.size.height);
float radius = (minSize-_strokeWidth)/2 -4;
CGPoint center = CGPointMake(self.frame.size.width/2,self.frame.size.height/2);
CAShapeLayer *circle = [CAShapeLayer layer];
circle.path = [UIBezierPath bezierPathWithArcCenter:center
radius:radius
startAngle:start_angle
endAngle:end_angle
clockwise:YES].CGPath;
circle.strokeColor = self.trackColor.CGColor;
circle.fillColor = nil;
circle.lineWidth = (_strokeWidth == -1.0) ? minSize * _strokeWidthRatio
: _strokeWidth;
circle.rasterizationScale = [[UIScreen mainScreen] scale];
return circle;
}

Answer 1

The picture you provided is exactly what happened to me. I got the chunky circle. In my case, the code was inside the drawRect method. The problem was that I was adding a CAShapeLayer, as a subLayer of my view, every time drawRect was called.
So to anyone who stumbles upon something similar, keep track of the CAShapeLayer you are adding or clear everything before drawing again in the drawRect.