在willdisplaycell:

cell.separatorInset = UIEdgeInsetsMake(0, cell.bounds.size.width, 0, 0)

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);
}

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;
}

更简单、更符合逻辑的做法是:

- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section
{
    return [[UIView alloc] initWithFrame:CGRectZero];
}

在大多数情况下，您不希望只看到最后一个表视图单元格分隔符。这种方法只删除了最后一个表格视图单元格分隔符，你不需要考虑自动布局问题(即旋转设备)或硬编码值来设置分隔符嵌入。

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)
    }
}

在iOS9上，我有一个问题，改变分隔符插入也会影响文本和细节标签的定位。

我用这个解出来了

override func layoutSubviews() {
    super.layoutSubviews()

    separatorInset = UIEdgeInsets(top: 0, left: layoutMargins.left, bottom: 0, right: width - layoutMargins.left)
}