Tableview 默认选中第一行以及选中背景自定义

//默认选中第一行
NSIndexPath *firstPath=[NSIndexPath indexPathForRow:0 inSection:0];
[_firstTableView selectRowAtIndexPath:firstPath animated:YES scrollPosition:UITableViewScrollPositionTop];

//选中背景自定义

cell.selectedBackgroundView=[[[UIImageView alloc]initWithImage:[UIImage imageNamed:@"cell_selected_bg"]]autorelease];