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)
    }
}

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);
}

使用这个子类，set separatorInset在iOS 9.2.1中不起作用，内容会被压缩。

@interface NSPZeroMarginCell : UITableViewCell

@property (nonatomic, assign) BOOL separatorHidden;

@end

@implementation NSPZeroMarginCell

- (void) layoutSubviews {
    [super layoutSubviews];

    for (UIView *view in  self.subviews) {
        if (![view isKindOfClass:[UIControl class]]) {
            if (CGRectGetHeight(view.frame) < 3) {
                view.hidden = self.separatorHidden;
            }
        }
    }
}

@end

https://gist.github.com/liruqi/9a5add4669e8d9cd3ee9

来跟进Hiren的回答。

在ViewDidLoad和下面一行:

self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone;

或者，如果你正在使用XIB或storyboard，将“separator”更改为“none”:

在CellForRowAtIndexPath中添加这个:

CGFloat separatorInset; // Separator x position 
CGFloat separatorHeight; 
CGFloat separatorWidth; 
CGFloat separatorY; 
UIImageView *separator;
UIColor *separatorBGColor;

separatorY      = cell.frame.size.height;
separatorHeight = (1.0 / [UIScreen mainScreen].scale);  // This assures you to have a 1px line height whatever the screen resolution
separatorWidth  = cell.frame.size.width;
separatorInset  = 15.0f;
separatorBGColor  = [UIColor colorWithRed: 204.0/255.0 green: 204.0/255.0 blue: 204.0/255.0 alpha:1.0];

separator = [[UIImageView alloc] initWithFrame:CGRectMake(separatorInset, separatorY, separatorWidth,separatorHeight)];
separator.backgroundColor = separatorBGColor;
[cell addSubView: separator];

这是一个结果的例子，我显示一个动态单元格的tableview(但只有一个内容)。结果是，只有一个有分隔符，而不是所有的“虚拟”tableview自动添加填充屏幕。

编辑:对于那些不经常阅读注释的人来说，实际上有一种更好的方法，只需几行代码:

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.tableFooterView = UIView()
}

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;
}