修改UISearchBar的背景

for(UIView *subView  in   searchBar.subviews){
	//NSLog(@"subView:%@",subView);
	if([subView isKindOfClass:NSClassFromString(@"UISearchBarBackground")]){
	[subView removeFromSuperview];
	}
}

UIImage *searchBarBackImage = [UIImage imageNamed:@"searchbar_bg"];
searchBarBackImage.frame = searchBar.frame;
searchBarBackImage.userInteractionEnabled = YES;
[searchBar  insertSubview:searchBarBackImage atIndex:0];

[searchBar setBackgroundImage:[UIImage imageNamed:@"searchbar_bg"]];