[ios] iOS 8 UITableView separator inset 0 not working

I have an app where the UITableView's separator inset is set to custom values - Right 0, Left 0. This works perfectly in iOS 7.x, however in iOS 8.0 I see that the separator inset is set to the default of 15 on the right. Even though in the xib files it set to 0, it still shows up incorrectly.

How do I remove the UITableViewCell separator margins?

simply put this two lines in cellForRowAtIndexPath method

• if you want to all separator lines are start from zero [cell setSeparatorInset:UIEdgeInsetsZero]; [cell setLayoutMargins:UIEdgeInsetsZero];

if you want to Specific separator line are start from zero suppose here is last line is start from zero

if (indexPath.row == array.count-1) 
{
   [cell setSeparatorInset:UIEdgeInsetsZero];
   [cell setLayoutMargins:UIEdgeInsetsZero];
}
else
   tblView.separatorInset=UIEdgeInsetsMake(0, 10, 0, 0);

Instead of updating preservesSuperviewLayoutMargins and layoutMargins every time the cell scrolls in (using willDisplayCell), I'd suggest to do it once in cellForRowAtIndexPath::

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

    let cell = super.tableView(tableView, cellForRowAtIndexPath: indexPath)

    cell.preservesSuperviewLayoutMargins = false
    cell.layoutMargins = UIEdgeInsetsZero

    return cell

}

For iOS 9 you need to add:

if([myTableView respondsToSelector:@selector(setCellLayoutMarginsFollowReadableWidth:)])
{
    myTableView.cellLayoutMarginsFollowReadableWidth = NO;
} 

For more details please refer to question.

Here's an easy way to globally remove the inset.

In UITableViewCell+Extensions.swift:

import UIKit

extension UITableViewCell {

  override public var layoutMargins: UIEdgeInsets {
    get { return UIEdgeInsetsZero }
    set { }
  }

}

In AppDelegate application:didFinishLaunchingWithOptions::

  UITableViewCell.appearance().separatorInset = UIEdgeInsetsZero

You might think to a) also just override separatorInset in the extension, or b) set the appearance proxy for layoutMargins, instead. Neither will work. Even though separatorInset is indicated to be a property, attempting to override it as a property (or method) generates compiler errors. And setting the appearance proxy for UITableViewCell's layoutMargins (or, for that matter, also setting the appearance proxies for UITableView's layoutMargins and separatorInset) has no effect.

This is my solution. This applies to the custom cell subclass, just add them both to the subclass.

1. - (UIEdgeInsets)layoutMargins {    
       return UIEdgeInsetsMake(0, 10, 0, 10);
   }
   

2.

self.separatorInset = UIEdgeInsetsMake(0, 10, 0, 10);

And it is convenient that you can customize the position of the separator without asking your designer to draw one for you..........

You can use UIAppearance once, at your application startup (before UI is loaded), to set it as default global settings:

// iOS 7:
[[UITableView appearance] setSeparatorStyle:UITableViewCellSeparatorStyleSingleLine];
[[UITableView appearance] setSeparatorInset:UIEdgeInsetsZero];

[[UITableViewCell appearance] setSeparatorInset:UIEdgeInsetsZero];

// iOS 8:
if ([UITableView instancesRespondToSelector:@selector(setLayoutMargins:)]) {

    [[UITableView appearance] setLayoutMargins:UIEdgeInsetsZero];
    [[UITableViewCell appearance] setLayoutMargins:UIEdgeInsetsZero];
    [[UITableViewCell appearance] setPreservesSuperviewLayoutMargins:NO];

}

This way, you keep your UIViewController's code clean and can always override it if you want.

Adding this snippet, simple elegant in Swift works for me in iOS8 :)

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

As to what cdstamper suggested instead of the table view, adding below lines in the cell's layoutSubview method works for me.

- (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];
        }
}

I didn't have any real luck with any of the solutions above. I'm using NIB files for my tables cells. I "fixed" this by adding a label with a height of 1. I changed the background of the label to black, pinned the label to the bottom of the nib, and then pinned the bottom of the rest of my contents to the added label. Now I have a black border running along the bottom of my cells.

To me, this feels like more of a hack, but it does work.

My only other choice was to just eliminate the border completely. I'm still deciding whether I'll just go with that.

following answer from @cdstamper, a better place is layoutSubviews of UITableViewCell, in your cell file(I set 1% spacing, you can set to zero), so need only to set code here to handle all situations(rotate and other):

 -(void)layoutSubviews
    {
        [super layoutSubviews];
        if ([self respondsToSelector:@selector(setSeparatorInset:)]) {
            [self setSeparatorInset:UIEdgeInsetsMake(0,self.bounds.size.width*0.01,0,self.bounds.size.width*0.01)];
        }
        if ([self respondsToSelector:@selector(setLayoutMargins:)]) {
            [self setLayoutMargins:UIEdgeInsetsMake(0,self.bounds.size.width*0.01,0,self.bounds.size.width*0.01)];
        }
    }

I made it work by doing this:

tableView.separatorInset = UIEdgeInsetsZero;
tableView.layoutMargins = UIEdgeInsetsZero;
cell.layoutMargins = UIEdgeInsetsZero;

I believe this is the same question that I asked here: Remove SeparatorInset on iOS 8 UITableView for XCode 6 iPhone Simulator

In iOS 8, there is one new property for all the objects inherit from UIView. So, the solution to set the SeparatorInset in iOS 7.x will not be able to remove the white space you see on the UITableView in iOS 8.

The new property is called "layoutMargins".

@property(nonatomic) UIEdgeInsets layoutMargins
Description   The default spacing to use when laying out content in the view.
Availability  iOS (8.0 and later)
Declared In   UIView.h
Reference UIView Class Reference

The solution:-

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(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];
   }
}

If you set cell.layoutMargins = UIEdgeInsetsZero; without checking if the layoutMargins exists, the app will crash on iOS 7.x. So, the best way would be checking if the layoutMargins exists first before setLayoutMargins:UIEdgeInsetsZero.

Let's take a moment to understand the problem before blindly charging in to attempt to fix it.

A quick poke around in the debugger will tell you that separator lines are subviews of UITableViewCell. It seems that the cell itself takes a fair amount of responsibility for the layout of these lines.

iOS 8 introduces the concept of layout margins. By default, a view's layout margins are 8pt on all sides, and they're inherited from ancestor views.

As best we can tell, when laying out out its separator line, UITableViewCell chooses to respect the left-hand layout margin, using it to constrain the left inset.

Putting all that together, to achieve the desired inset of truly zero, we need to:

• Set the left layout margin to 0
• Stop any inherited margins overriding that

Put like that, it's a pretty simple task to achieve:

cell.layoutMargins = UIEdgeInsetsZero;
cell.preservesSuperviewLayoutMargins = NO;

Things to note:

• This code only needs to be run once per cell (you're just configuring the cell's properties after all), and there's nothing special about when you choose to execute it. Do what seems cleanest to you.
• Sadly neither property is available to configure in Interface Builder, but you can specify a user-defined runtime attribute for preservesSuperviewLayoutMargins if desired.
• Clearly, if your app targets earlier OS releases too, you'll need to avoid executing the above code until running on iOS 8 and above.
• Rather than setting preservesSuperviewLayoutMargins, you can configure ancestor views (such as the table) to have 0 left margin too, but this seems inherently more error-prone as you don't control that entire hierarchy.
• It would probably be slightly cleaner to set only the left margin to 0 and leave the others be.
• If you want to have a 0 inset on the "extra" separators that UITableView draws at the bottom of plain style tables, I'm guessing that will require specifying the same settings at the table level too (haven't tried this one!)

For me none has worked except this workaround (Swift 3.0):

extension UIColor {
    static func colorWith(hex:String, alpha: CGFloat) -> UIColor {
        var cString = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()

        if cString.hasPrefix("#") {
            cString.remove(at: cString.startIndex)
        }

        if cString.characters.count != 6 {
            return UIColor.gray
        }

        var rgbValue:UInt32 = 0
        Scanner(string: cString).scanHexInt32(&rgbValue)

        return UIColor(red:   CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
                       green: CGFloat((rgbValue & 0x00FF00) >> 8)  / 255.0,
                       blue:  CGFloat( rgbValue & 0x0000FF)        / 255.0,
                       alpha: alpha)
    }
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: cellReuseIdendifier, for: indexPath)

    cell.backgroundColor = UIColor.colorWith(hex: "c8c7cc", alpha: 1) // same color of line separator

    return cell
}

After having seen the answers at floor 3, I tried to figure out what the relationship of setting up the separator between TableView & TableViewCell and did some test. Here are my conclusions:

1. we can consider that setting the cell's separator to zero has to move the separator in two steps: first step is to set cell's separatorinset to zero. second step is to set cell's marginlayout to zero.

2. set the TableView's separatorinset and marginlayout can affect the Cell's separatorinset. However, from the test, I find that the TableView's separatorinset seem to be useless, TableView's marginlayout can actually affect cell's marginlayout.

3. set Cell's PreservesSuperviewLayoutMargins = false, can cut off TableView's marginlayout effect on Cells.

4. one of the solutions:

   func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
       var cell = UITableViewCell()
   
       cell.preservesSuperviewLayoutMargins = false
       cell.separatorInset = UIEdgeInsetsZero
       cell.layoutMargins = UIEdgeInsetsZero
   
       return cell
   }
   

For me the simple line did the job

cell.layoutMargins = UIEdgeInsetsZero

Swift:

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
}

This is the code that's working for me, in Swift:

override func viewDidLoad() 
{
    super.viewDidLoad()
    ...
    if tableView.respondsToSelector("setSeparatorInset:") {
        tableView.separatorInset = UIEdgeInsetsZero
    }
}

func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell,forRowAtIndexPath indexPath: NSIndexPath)
{
    if cell.respondsToSelector("setSeparatorInset:") {
        cell.separatorInset.left = CGFloat(0.0)
    }
    if tableView.respondsToSelector("setLayoutMargins:") {
        tableView.layoutMargins = UIEdgeInsetsZero
    }
    if cell.respondsToSelector("setLayoutMargins:") {
        cell.layoutMargins.left = CGFloat(0.0)
    }
}

This seems the cleanest to me (for now), as all the cell/tableView edge/margin adjustments are done in the tableView:willDisplayCell:forRowAtIndexPath: method, without cramming unneccessary code into tableView:cellForRowAtIndexPath:.

Btw, I'm only setting the cell's left separatorInset/layoutMargins, because in this case I don't want to screw up my constraints that I have set up in my cell.

Code updated to Swift 2.2 :

 override func viewDidLoad() {
   super.viewDidLoad()       

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

 override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell,forRowAtIndexPath indexPath: NSIndexPath) {
        if cell.respondsToSelector(Selector("setSeparatorInset:")) {
            cell.separatorInset.left = CGFloat(0.0)
        }
        if tableView.respondsToSelector(Selector("setLayoutMargins:")) {
            tableView.layoutMargins = UIEdgeInsetsZero
        }
        if cell.respondsToSelector(Selector("setLayoutMargins:")) {
            cell.layoutMargins.left = CGFloat(0.0)
        }
    }

XCode 7.1 iOS 7, 8, 9:

just put these two lines in your TabelViewCell:

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

That worked for me

I went through all these wonderful answers and realized most of them do not work with iOS 8, or do work but the separator changes size during animation causing unwanted flashing. This is what I ended up doing in my app delegate before creating the window:

[[UITableView appearance] setSeparatorInset:UIEdgeInsetsZero];
[[UITableViewCell appearance] setSeparatorInset:UIEdgeInsetsZero];

if ([UITableView instancesRespondToSelector:@selector(setLayoutMargins:)]) {
    [[UITableView appearance] setLayoutMargins:UIEdgeInsetsZero];
    [[UITableViewCell appearance] setLayoutMargins:UIEdgeInsetsZero];
    [[UITableViewCell appearance] setPreservesSuperviewLayoutMargins:NO];
}

And this is what I added to my UITableViewController:

-(void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
        [self.tableView setSeparatorInset:UIEdgeInsetsZero];
    }

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

I didn't need to add anything else. Thanks to everyone who provided the crucial bits.

iOS introduces the layoutMargins property on cells AND table views.

This property isn't available in iOS 7.0 so you need to make sure you check before assigning it!

However, Apple has added a property called preservesSuperviewLayoutMargins to your cell that will prevent it from inheriting your Table View's margin settings. This way, your cells can configure their own margins independently of the table view. Think of it as an override.

This property is called preservesSuperviewLayoutMargins, and setting it to NO can allow you to override your Table View's layoutMargin settings with your own cell's layoutMargin setting. It both saves time (you don't have to modify the Table View's settings), and is more concise. Please refer to Mike Abdullah's answer for a detailed explanation.

NOTE: this is the proper, less messy implementation, as expressed in Mike Abdullah's answer; setting your cell's preservesSuperviewLayoutMargins=NO will ensure that your Table View does not override the cell settings.

First step - Setup your cell margins:

/*
    Tells the delegate that the table view is about to draw a cell for a particular row.
*/
override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell,
    forRowAtIndexPath indexPath: NSIndexPath)
{
    // Remove separator inset
    if cell.respondsToSelector("setSeparatorInset:") {
        cell.separatorInset = UIEdgeInsetsZero
    }

    // Prevent the cell from inheriting the Table View's margin settings
    if cell.respondsToSelector("setPreservesSuperviewLayoutMargins:") {
        cell.preservesSuperviewLayoutMargins = false
    }

    // Explictly set your cell's layout margins
    if cell.respondsToSelector("setLayoutMargins:") {
        cell.layoutMargins = UIEdgeInsetsZero
    }
}

Setting the preservesSuperviewLayoutMargins property on your cell to NO should prevent your table view from overriding your cell margins. In some cases, it seems not to function properly.

Second step - Only if all fails, you may brute-force your Table View margins:

/*
    Called to notify the view controller that its view has just laid out its subviews.
*/
override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()

    // Force your tableview margins (this may be a bad idea)
    if self.tableView.respondsToSelector("setSeparatorInset:") {
        self.tableView.separatorInset = UIEdgeInsetsZero
    }

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

...and there you go! This should work on iOS 8 as well as iOS 7.

Note: tested using iOS 8.1 and 7.1, in my case I only needed to use the first step of this explanation.

The Second Step is only required if you have unpopulated cell beneath the rendered cells, ie. if the table is larger than the number of rows in the table model. Not doing the second step would result in different separator offsets.

My solution is adding an UIView as a container for the cell subviews. Then set this UIView constraints (top,bottom,trailing,leading) to 0 points. And all the unnecessary mass go away.the image showing the logic

After much investigation...

Here's the only way to fully control this stuff (that I could find)

To fully control both separator insets and layout margins on each cell. Do this in the willDisplayCell method on your UITableviewDelegate.

func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {
    cell.layoutMargins = UIEdgeInsetsZero
    cell.contentView.layoutMargins = UIEdgeInsetsMake(0, 10, 0, 10)
    cell.separatorInset = UIEdgeInsetsMake(0, 0, 0, 0)
}

The cell object controls the separator, and the contentView controls everything else. If your separator inset spaces are showing up in an unexpected color this should solve it:

cell.backgroundColor = cell.contentView.backgroundColor

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
        // ... Get the cell
        cell.separatorInset = UIEdgeInsetsMake(0.f, 20.f, 0.f, [UIScreen mainScreen].bounds.size.width - 20);
        // others
        return cell;
}

For any specific cell you want to hide the separator.

Arg!!! After playing around either doing this in your Cell subclass:

- (UIEdgeInsets)layoutMargins
{
    return UIEdgeInsetsZero;
}

or setting the cell.layoutMargins = UIEdgeInsetsZero; fixed it for me.

In iOS8:

Adding this to my UITableViewCell Subclass:

- (UIEdgeInsets)layoutMargins {
    return UIEdgeInsetsZero;
}

and this to "tableView:cellForRowAtIndexPath" or "tableView:willDisplayCell":

[editCell setSeparatorInset:UIEdgeInsetsZero];

WORKED for me.

iOS 8 and later. Swift 2.0 and later:

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
    }
}

Just override the "cellForRowAtIndexPath" and set "cell.preservesSuperviewLayoutMargins = false" and "cell.separatorInset = UIEdgeInsets.zero" and "cell.layoutMargins = UIEdgeInsets.zero"

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

    let cell: LayoutTableViewCell! = tableView.dequeueReusableCell(withIdentifier: "LayoutCell") as? LayoutTableViewCell



    let currentLayout = OrderLayouts()[indexPath.row]

    cell.NameLabel?.text = currentLayout.name
    cell.DescrLabel?.text = currentLayout.descr

    if(GlobalVariables.debug){

        cell.DescrLabel?.text = "\(currentLayout.id) \n \(currentLayout.descr)"

    }

    cell.preservesSuperviewLayoutMargins = false
    cell.separatorInset = UIEdgeInsets.zero
    cell.layoutMargins = UIEdgeInsets.zero


    return cell

}

use storyboard to Change Separator inset Custom left 0 and right 0, if you want to hide separator to None see above image

Lukasz answer in Swift:

    // 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
    }

Swift 2.0 Extension

I just wanted to share an extension I made to remove the margins from the tableview cell separators.

extension UITableViewCell {
    func removeMargins() {

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

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

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

Used in context:

    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! CustomCell

    cell.removeMargins()
    return cell

This worked perfectly for me in iOS 8 and iOS 9.

For 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;
    }

let do as my code:

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

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

    if ([tableView respondsToSelector:@selector(setLayoutMargins:)]) {
        cell.preservesSuperviewLayoutMargins = NO;
        [cell setLayoutMargins:UIEdgeInsetsZero];
    }
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]){
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }
}

Just add below code can solve this program.

Good luck to you!

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {

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

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

}

Use below code snippet avoid unwanted padding issue for UITableView in IOS 8 & 7.

-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(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];
    }
}

With Swift 2.2

create UITableViewCell extension

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
        }
    }
} 

Now you can use in your cellForRowAtIndex

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

Swift 3.0 example:

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    // removing seperator inset
    if cell.responds(to: #selector(setter: UITableViewCell.separatorInset)) {
        cell.separatorInset = .zero
    }
    // prevent the cell from inheriting the tableView's margin settings
    if cell.responds(to: #selector(setter: UIView.preservesSuperviewLayoutMargins)) {
        cell.preservesSuperviewLayoutMargins = false
    }
    // explicitly setting cell's layout margins
    if cell.responds(to: #selector(setter: UITableViewCell.layoutMargins)) {
        cell.layoutMargins = .zero
    }
}

In Swift it's slightly more annoying because layoutMargins is a property, so you have to override the getter and setter.

override var layoutMargins: UIEdgeInsets {
  get { return UIEdgeInsetsZero }
  set(newVal) {}
}

This will effectively make layoutMargins readonly, which in my case is fine.

Simple solution in Swift for iOS 8 with a custom UITableViewCell

override func awakeFromNib() {
    super.awakeFromNib()

    self.layoutMargins = UIEdgeInsetsZero
    self.separatorInset = UIEdgeInsetsZero
}

In this way you are setting layoutMargin and separatorInset just one time instead of doing it for each willDisplayCell as most of the above answers suggest.

If you are using a custom UITableViewCell this is the correct place to do it. Otherwise you should do it in tableView:cellForRowAtIndexPath.

Just another hint: you don't need to set preservesSuperviewLayoutMargins = false because default value is already NO!

Most answers are showing separator insets and layout margins being set over a variety of methods (i.e., viewDidLayoutSubviews, willDisplayCell, etc) for cells and tableviews, but I've found that just putting these in cellForRowAtIndexPath works great. Seems like the cleanest way.

// 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];

In Swift you can use this

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

In a more compact way than the most voted answer...

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {

    if ([cell respondsToSelector:@selector(setSeparatorInset:)] && [cell respondsToSelector:@selector(setPreservesSuperviewLayoutMargins:)] && [cell respondsToSelector:@selector(setLayoutMargins:)]) {
         [cell setSeparatorInset:UIEdgeInsetsZero];
         [cell setPreservesSuperviewLayoutMargins:NO];
         [cell setLayoutMargins:UIEdgeInsetsZero];
    }

}