UIView（视图）

lazy var bgView: UIView = {
        
        let view = UIView ()
        view.backgroundColor = UIColor.white
        
        return view
    }()

       bgView.snp.makeConstraints { (make) -> Void in
        make.width.equalTo(50)
        make.height.equalTo(50)
        make.center.equalTo(self.view)
       }

线

       lineView.snp.makeConstraints { (make) -> Void in
        make.left.equalTo(self.contentView);
        make.right.equalTo(self.contentView);
        make.bottom.equalTo(self.descLable.top);
        make.height.equalTo(1);
       }

顶部圆角

        let bgView = UIView ()
        bgView.frame = CGRect.init(x: 50, y: 80, width: 100, height: 100)
        bgView.backgroundColor = UIColor.gray
        self.view.addSubview(bgView)
        
        
        let maskPath = UIBezierPath.init(roundedRect: view.bounds, byRoundingCorners: .topLeft , cornerRadii: CGSize(width: 10, height: 10))
        let maskLayer = CAShapeLayer.init()
        maskLayer.frame = view.bounds
        maskLayer.path = maskPath.cgPath
        bgView.layer.mask = maskLayer