viewForBaselineLayout

发现iOS6里面新添加的一个UIView的属性，可以做什么，你懂得！！！

- (UIView *)viewForBaselineLayoutNS_AVAILABLE_IOS(6_0);

代码如下：

   UIImageView *bgshow = [UIImageViewnew];

    [bgshowsetFrame:CGRectMake(0,0, CGRectGetWidth(self.bounds),0.5)];

    bgshow.backgroundColor= [UIColorcolorWithRed:23.0/255.0green:28.0/255.0blue:36.0/255.0alpha:0.3];

    [self.viewForBaselineLayoutaddSubview:bgshow];