iOS 8及更高版本。Swift 2.0及更高版本:

override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
    cell.separatorInset = UIEdgeInsetsZero
    if #available(iOS 8.0, *) {
        cell.layoutMargins = UIEdgeInsetsZero
    } else {
        // Fallback on earlier versions
    }
}

这在我的iOS 8和iOS 9系统中运行得非常好。

对于OBJ-C

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath  { 
        if ([tableView respondsToSelector:@selector(setSeparatorInset:)])
        {
            [tableView setSeparatorInset:UIEdgeInsetsZero];
        }

        if ([tableView respondsToSelector:@selector(setLayoutMargins:)])
        {
            [tableView setLayoutMargins:UIEdgeInsetsZero];
        }

        if ([cell respondsToSelector:@selector(setLayoutMargins:)])
        {
            [cell setLayoutMargins:UIEdgeInsetsZero];
        }
         return cell;
    }

迅速:

override func viewDidLoad() {
    super.viewDidLoad()

    if self.tableView.respondsToSelector("setSeparatorInset:") {
        self.tableView.separatorInset = UIEdgeInsetsZero
    }
    if self.tableView.respondsToSelector("setLayoutMargins:") {
        self.tableView.layoutMargins = UIEdgeInsetsZero
    }

    self.tableView.layoutIfNeeded()            // <--- this do the magic
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
     ...

    if cell.respondsToSelector("setSeparatorInset:") {
        cell.separatorInset = UIEdgeInsetsZero
    }
    if cell.respondsToSelector("setLayoutMargins:") {
        cell.layoutMargins = UIEdgeInsetsZero
    }

    return cell
}

至于cdstamper建议的表格视图，在单元格的layoutSubview方法中添加以下行对我来说是可行的。

- (void)layoutSubviews 
{
    [super layoutSubviews];

    if ([self respondsToSelector:@selector(setSeparatorInset:)])
                [self setSeparatorInset:UIEdgeInsetsZero];

        if ([self respondsToSelector:@selector(setPreservesSuperviewLayoutMargins:)])
        {
            [self setPreservesSuperviewLayoutMargins:NO];;
        }

        if ([self respondsToSelector:@selector(setLayoutMargins:)]) 
        {
            [self setLayoutMargins:UIEdgeInsetsZero];
        }
}

Lukasz用Swift回答:

    // iOS 7:
    UITableView.appearance().separatorStyle = .SingleLine
    UITableView.appearance().separatorInset = UIEdgeInsetsZero
    UITableViewCell.appearance().separatorInset = UIEdgeInsetsZero

    // iOS 8:
    if UITableView.instancesRespondToSelector("setLayoutMargins:") {
        UITableView.appearance().layoutMargins = UIEdgeInsetsZero
        UITableViewCell.appearance().layoutMargins = UIEdgeInsetsZero
        UITableViewCell.appearance().preservesSuperviewLayoutMargins = false
    }

使用storyboard更改分隔符插入自定义左0和右0， 如果你想隐藏分隔符为None 见上图