如何删除UIView底部边框？

Question

UIBezierPath *maskDefault = [UIBezierPath bezierPath];
[maskDefault moveToPoint:CGPointMake(0.0, 0.0)];
[maskDefault addLineToPoint:CGPointMake(width, 0.0)];
[maskDefault addLineToPoint:CGPointMake(width, height * 0.8)];
[maskDefault addLineToPoint:CGPointMake(width * 0.8, height)];
[maskDefault addLineToPoint:CGPointMake(width * 0.2, height)];
[maskDefault addLineToPoint:CGPointMake(0.0, height * 0.8)];
[maskDefault closePath];

CAShapeLayer *maskingDefulatLayer = [CAShapeLayer layer];
maskingDefulatLayer.path = maskDefault.CGPath;

CAShapeLayer *maskingLayer = [CAShapeLayer layer];
maskingLayer.path = maskDefault.CGPath;

self.uiView.layer.mask = maskingDefulatLayer;

我想删除底部边框，就像第二张图片一样。

帮帮我