UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomRight | UIRectCornerTopRight cornerRadii:CGSizeMake(40, 40)];

    // 这里 40 40 表示圆弧的角度  前面的参数有四个类型  左上角  左下角  右上角  右下角      CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];       maskLayer.frame = view2.bounds;        maskLayer.path = maskPath.CGPath;        view2.layer.mask = maskLayer;