CAShapeLayer custom property is nil when drawInContext - uibezierpath

Question

I denfined a custom layer,and declare a custom property,but it's not work when animation in -(void)drawInContext:(CGContextRef)ctx method
here is some code:
#interface ZBBProgressLayer : CAShapeLayer
#property (nonatomic, assign) CGFloat progress;
#property(nullable) CGColorRef progressColor;
#end
#implementation ZBBProgressLayer
+ (BOOL)needsDisplayForKey:(NSString *)key{
if ([key isEqualToString:#"progress"]/*progress 属性变化时，重绘*/) {
return YES;
}
return [super needsDisplayForKey:key];
}
-(void)dealloc{
[self removeAllAnimations];
}
#end
// ZBBRectProgressLayer
#interface ZBBRectProgressLayer : ZBBProgressLayer
#end
#implementation ZBBRectProgressLayer
-(void)drawInContext:(CGContextRef)ctx{
CGSize boundsSize = self.bounds.size;
CGFloat width = boundsSize.width * self.progress;
UIBezierPath *cutoutPath =[UIBezierPath bezierPathWithRect:CGRectMake(0,
0,
width,
boundsSize.height)];
CGContextSetFillColorWithColor(ctx,self.progressColor);
CGContextAddPath(ctx, cutoutPath.CGPath);
CGContextFillPath(ctx);
// NSLog(#"%# = %#\n",[self class],self);
}
#end
I use the layer like this:
-(void)setProgress:(CGFloat)progress animated:(BOOL)animated{
_progress = MIN(progress, 1);
if (animated) {
CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:#"progress"];
animation.duration = kAnimationDurationTime;
animation.fromValue = #(_maskLayer.progress);
animation.toValue = #(_progress);
[_maskLayer addAnimation:animation forKey:#"progress"];
_maskLayer.progress = _progress;
}else{
_maskLayer.progress = _progress;
[_maskLayer performSelectorOnMainThread:#selector(setNeedsDisplay) withObject:nil waitUntilDone:YES];
}
}
but animated == true,custom layer.progressColor is nil,
animated == false,custom layer.progressColor is right.
source code : https://github.com/zhangbinbin5335/ZBBProgressView.git