试试下面的代码，也许能帮你解决问题

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

   NSString* reuseIdentifier = @"Contact Cell";

    UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier];
    if (nil == cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier];
if (indexPath.row != 10) {//Specify the cell number
        cell.backgroundView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"bgWithLine.png"]];

} else {
        cell.backgroundView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"bgWithOutLine.png"]];

}

    }

    return cell;
}

除非使用以下解决方法，否则无法在特定单元格上隐藏分隔符

- (void)layoutSubviews {
    [super layoutSubviews];
    [self hideCellSeparator];
}
// workaround
- (void)hideCellSeparator {
    for (UIView *view in  self.subviews) {
        if (![view isKindOfClass:[UIControl class]]) {
            [view removeFromSuperview];
        }
    }
}

在viewDidLoad中添加这一行:

self.tableView.separatorColor = [UIColor clearColor];

在cellForRowAtIndexPath中:

适用于iOS低版本

if(indexPath.row != self.newCarArray.count-1){
    UIImageView *line = [[UIImageView alloc] initWithFrame:CGRectMake(0, 44, 320, 2)];
    line.backgroundColor = [UIColor redColor];
    [cell addSubview:line];
}

适用于iOS 7以上版本(包括iOS 8)

if (indexPath.row == self.newCarArray.count-1) {
    cell.separatorInset = UIEdgeInsetsMake(0.f, cell.bounds.size.width, 0.f, 0.f);
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

       NSString *cellId = @"cell";
       UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellId];
       NSInteger lastRowIndexInSection = [tableView numberOfRowsInSection:indexPath.section] - 1;

       if (row == lastRowIndexInSection) {
              CGFloat halfWidthOfCell = cell.frame.size.width / 2;
              cell.separatorInset = UIEdgeInsetsMake(0, halfWidthOfCell, 0, halfWidthOfCell);
       }
}

iphone的宽度是320。因此，在单元格属性中为separatorInset设置左右值，大于320的一半。

在使用iOS 8.4的Swift中:

/*
    Tells the delegate that the table view is about to draw a cell for a particular row. (optional)
*/
override func tableView(tableView: UITableView,
                        willDisplayCell cell: UITableViewCell,
                        forRowAtIndexPath indexPath: NSIndexPath)
{
    if indexPath.row == 3 {
        // Hiding separator line for only one specific UITableViewCell
        cell.separatorInset = UIEdgeInsetsMake(0, cell.bounds.size.width, 0, 0)
    }
}

Note: this snippet above will work on UITableView using dynamic cells. The only problem that you can encounter is when you use static cells with categories, a separator type different than none and a grouped style for the table view. In fact, in this particular case it will not hide the last cell of each category. For overcoming that, the solution that I found was to set the cell separator (through IB) to none and then creating and adding manually (through code) your line view to each cell. For an example, please check the snippet below:

/*
Tells the delegate that the table view is about to draw a cell for a particular row. (optional)
*/
override func tableView(tableView: UITableView,
    willDisplayCell cell: UITableViewCell,
    forRowAtIndexPath indexPath: NSIndexPath)
{
    // Row 2 at Section 2
    if indexPath.row == 1 && indexPath.section == 1 {
        // Hiding separator line for one specific UITableViewCell
        cell.separatorInset = UIEdgeInsetsMake(0, cell.bounds.size.width, 0, 0)

        // Here we add a line at the bottom of the cell (e.g. here at the second row of the second section).
        let additionalSeparatorThickness = CGFloat(1)
        let additionalSeparator = UIView(frame: CGRectMake(0,
            cell.frame.size.height - additionalSeparatorThickness,
            cell.frame.size.width,
            additionalSeparatorThickness))
        additionalSeparator.backgroundColor = UIColor.redColor()
        cell.addSubview(additionalSeparator)
    }
}