画空心圆或者空心矩形

CAShapeLayer *pShapeLayer = [CAShapeLayer layer];

pShapeLayer.fillColor = [UIColor colorWithHex:0x000000 alpha:0.75].CGColor;

[button.layer addSublayer:pShapeLayer];

UIBezierPath *pPath = [UIBezierPath bezierPathWithArcCenter:button.center radius:50 startAngle:0.0 endAngle:M_PI*2 clockwise:YES];

pShapeLayer.path = pPath.CGPath;

UIBezierPath *pRPath = [UIBezierPath bezierPathWithRect:CGRectMake(100, 100, 150, 150)];

pShapeLayer.path = pRPath.CGPath;

UIBezierPath *pOtherPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, kScreenWidth, kScreenHeight)];

pShapeLayer.path = pOtherPath.CGPath;

[pOtherPath appendPath:pPath];

[pOtherPath appendPath:pRPath];

pShapeLayer.path = pOtherPath.CGPath;

//重点

pShapeLayer.fillRule = kCAFillRuleEvenOdd;