去掉UISearchBar自带的的边框背景 ，分为ios7后和ios7前的解决方案，代码如下：
UISearchBar* searchbar = [[UISearchBar alloc]initWithFrame:CGRectMake(5, 0, 310, 50)];
searchbar.tag = 1000;
searchbar.delegate = self;
[cell addSubview:searchbar];
for (UIView *view in searchbar.subviews) {
// for before iOS7.0
if ([view isKindOfClass:NSClassFromString(@"UISearchBarBackground")]) {
[view removeFromSuperview];
break;
}
// for later iOS7.0(include)
if ([view isKindOfClass:NSClassFromString(@"UIView")] && view.subviews.count > 0) {
[[view.subviews objectAtIndex:0] removeFromSuperview];
break;
}
}
原文：http://blog.csdn.net/intheair100/article/details/45744475