使用Swift 2.2

创建UITableViewCell扩展

import UIKit

extension UITableViewCell {
    func removeMargins() {

        if self.respondsToSelector(Selector("setSeparatorInset:")) {
            self.separatorInset = UIEdgeInsetsZero
        }

        if self.respondsToSelector(Selector("setPreservesSuperviewLayoutMargins:")) {
            self.preservesSuperviewLayoutMargins = false
        }

        if self.respondsToSelector(Selector("setLayoutMargins:")) {
            self.layoutMargins = UIEdgeInsetsZero
        }
    }
} 

现在可以在cellForRowAtIndex中使用

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
            cell.removeMargins()//To remove seprator inset 
}

大多数答案是显示分隔符插入和布局边距设置在各种方法(即viewDidLayoutSubviews, willDisplayCell等)的单元格和表视图，但我发现，只是把这些cellForRowAtIndexPath工作得很好。似乎是最干净的方法。

// kill insets for iOS 8
if ([[UIDevice currentDevice].systemVersion floatValue] >= 8) {
    cell.preservesSuperviewLayoutMargins = NO;
    [cell setLayoutMargins:UIEdgeInsetsZero];
}
// iOS 7 and later
if ([cell respondsToSelector:@selector(setSeparatorInset:)])
    [cell setSeparatorInset:UIEdgeInsetsZero];

XCode 7.1 iOS 7,8,9:

把这两行放到你的TabelViewCell中:

    self.layoutMargins = UIEdgeInsetsZero;
    self.preservesSuperviewLayoutMargins = false;

这对我很有用

在Swift中你可以使用这个

    cell.selectionStyle = UITableViewCellSelectionStyle.None
    cell.preservesSuperviewLayoutMargins = false
    cell.separatorInset = UIEdgeInsetsZero
    cell.layoutMargins = UIEdgeInsetsZero

使用Swift 2.2

创建UITableViewCell扩展

import UIKit

extension UITableViewCell {
    func removeMargins() {

        if self.respondsToSelector(Selector("setSeparatorInset:")) {
            self.separatorInset = UIEdgeInsetsZero
        }

        if self.respondsToSelector(Selector("setPreservesSuperviewLayoutMargins:")) {
            self.preservesSuperviewLayoutMargins = false
        }

        if self.respondsToSelector(Selector("setLayoutMargins:")) {
            self.layoutMargins = UIEdgeInsetsZero
        }
    }
} 

现在可以在cellForRowAtIndex中使用

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
            cell.removeMargins()//To remove seprator inset 
}

添加这个片段，简单优雅的Swift适用于我在iOS8:)

    // tableview single line
func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
    cell.preservesSuperviewLayoutMargins = false
    cell.layoutMargins = UIEdgeInsetsZero
}