Can't remove CAShapeLayer from Super Layer - ios

Question

I'm trying to remove my circle that I've created as a CAShapeLayer and drawn with UIBezier path if I can't receive a measurement. In my (void)drawRect method for my UIView class, I create and draw a circle if a measurement is found. However, if there is no measurement I'd like to get rid of the circle. For some reason I can't.
Here is the code that creates the circle in -(void)drawRect
- (void)drawRect:(CGRect)rect {
CAShapeLayer *grayCircle = [CAShapeLayer layer];
CAShapeLayer *progressArc = [CAShapeLayer layer];
DBHelper *dbHelper = [DBHelper getSharedInstance];
if ([dbHelper getPairedDevice]==nil) {
[grayCircle removeFromSuperlayer]; // I want to remove the grayCirle if no measurement is found AKA getPairedDevice = nil
}
....
if (_latestMeasurement) {
...
// Gray outer circle
UIBezierPath *grayCirclePath=[UIBezierPath bezierPathWithArcCenter:CGPointMake(radius, radius) radius:radius startAngle:startAngle endAngle:endAngle clockwise:YES];
grayCircle.path = [grayCirclePath CGPath];
grayCircle.position = CGPointMake(realBounds.origin.x, realBounds.origin.y);
grayCircle.fillColor = [UIColor clearColor].CGColor;
grayCircle.lineCap=kCALineCapRound;
grayCircle.strokeColor = [UIColor grayColor].CGColor;
grayCircle.lineWidth = 30;
// Progress arc
UIBezierPath *progressPath=[UIBezierPath bezierPathWithArcCenter:CGPointMake(radius, radius) radius:radius startAngle:startAngle endAngle:patientOutput clockwise:YES];
progressArc.path = [progressPath CGPath];
progressArc.position = CGPointMake(grayCircle.frame.origin.x, grayCircle.frame.origin.y);
progressArc.fillColor = [UIColor clearColor].CGColor;
progressArc.lineCap=kCALineCapRound;
progressArc.lineWidth = 30;
[self.layer addSublayer:grayCircle];
[self.layer addSublayer:progressArc];
}
So here's the issue: The following lines of code aren't removing the gray circle:
if ([dbHelper getPairedDevice]==nil) {
[grayCircle removeFromSuperlayer];
}
I'm wondering why is that the case, and how can I remove it from the view's sublayer?

Answer 1

You are creating a new reference to grayCircle each time you go through drawRect. When you remove it - you're removing the new one, not the one you drew previously.
If you already have it, you need to find it first, then remove it - going through the subViews, or maintain a reference to it at the class level