iOS 8 UITableView separator inset 0 not working: A Complete Guide for Beginners

Why doesn't separator inset 0 work in iOS 8? Getting to know the problem

Imagine: you're writing your first iPhone app, the table looks great on the iOS 14 simulator, but when you test it on an old iPhone 6 with iOS 8… bam! The cell separators behave unpredictably. You set separatorInset = .zero, but the left margins still remain. Sound familiar?

This problem — iOS 8 UITableView separator inset 0 not working — is a real "stumbling block" for beginner iOS developers. On Stack Overflow, this question has gathered thousands of views, and for good reason. In this article, we won't just give you a ready-made solution; we'll also understand why this happens and how to avoid similar pitfalls in the future.

If you're just starting to learn Swift and UIKit, don't worry — we'll go through the entire process step by step. By the end of the article, you won't just fix the bug, but you'll also understand how UITableView works at a deep level.

The root of the evil: what is separatorInset and why does iOS 8 ignore it?

Before treating, we need to understand the diagnosis. SeparatorInset is a property of UITableViewCell (and the table itself) that controls the margins of the separator line between cells. By default, iOS adds a small left margin (15 points) so the separator doesn't start right from the edge of the screen.

When you write:

cell.separatorInset = UIEdgeInsets.zero

…you expect the line to go from edge to edge. But in iOS 8 (and earlier versions), this doesn't happen. Why?

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• Reason 1: In iOS 8, the separatorInset property on the cell doesn't always override the table's global settings.
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• Reason 2: There is a "magical" property called layoutMargins that takes priority over separatorInset in iOS 8. Apple didn't document this behavior, and many developers got caught out.
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• Reason 3: The system adds margins by default via preservesSuperviewLayoutMargins, which is always enabled in iOS 8.
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In short: you tell the cell "set the margin to 0", and it replies "no, I obey the table and its layoutMargins".

Step-by-step solution: how to make separator inset work in iOS 8

Here is a proven recipe that worked in iOS 8 and still works today. We'll act on three levels: table → cell → layoutMargins.

Step 1. Configuring UITableView (global level)

The most reliable way is to set the margins for the entire table at once, in viewDidLoad:

override func viewDidLoad() {\n    super.viewDidLoad()\n    \n    // Disable extra margins for the table\n    tableView.separatorInset = .zero\n    tableView.layoutMargins = .zero\n    \n    // Important for iOS 8: prevent cells from inheriting margins from the table\n    tableView.preservesSuperviewLayoutMargins = false\n}

These three lines are your basic protection. But sometimes this isn't enough, and you need to fine-tune at the cell level.

Step 2. Configuring each cell (local level)

In the cellForRowAt method, add:

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {\n    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)\n    \n    // Override cell settings\n    cell.separatorInset = .zero\n    cell.layoutMargins = .zero\n    cell.preservesSuperviewLayoutMargins = false\n    \n    // Configure content\n    cell.textLabel?.text = "Row \\(indexPath.row)"\n    \n    return cell\n}

Note: we are duplicating the settings. This is not a mistake — this way we guarantee that the cell overrides any global table settings.

Step 3. (Optional)