I’m working with a UICollectionView that scrolls horizontally and has paging turned on. Each cell takes up the full width and height of the collection view, so only one cell shows at a time. I’m using custom cells for this setup.
The issue I’m facing is that when I swipe to move from the first cell to the second cell, there’s a weird jerky movement or stutter. After that first swipe though, scrolling between other cells works perfectly smooth.
In my cellForItemAt method, I’m not doing anything complex - just setting up the cell with data from an array. No heavy processing or image loading that should cause this behavior.
Has anyone experienced this kind of stuttering on the initial scroll in a paged collection view? What could be causing this first-time animation glitch?
Had this exact issue a few months ago. It’s your autolayout constraints in the custom cells. First swipe makes the collection view calculate frame sizes for cells that haven’t been laid out yet - that’s your stutter.
I fixed it by overriding prepareForReuse in my custom cell and caching all constraint calculations. Also, if you’re setting constraints in cellForItemAt, don’t. Move that to cell initialization instead.
The collection view’s initial measurement pass kills smooth animation. Less layout work during first swipe = smoother performance.
Yeah, this happens because of cell registration timing. The collection view needs to create and configure that second cell from scratch during your first swipe - that’s what causes the stutter. Once cells exist in the reuse pool, scrolling gets smooth. I hit this exact issue last year. Fixed it by pre-loading the adjacent cells - just call cellForItemAt programmatically in viewDidAppear for indexes 1 and 2, then toss them back into the reuse pool. Now the heavy cell creation happens upfront instead of during scrolling. You can also cut down on cell creation overhead by moving view setup code from cellForItemAt into the cell’s awakeFromNib or init method.
You’re experiencing jerky or stuttering movement when swiping between pages in your horizontally scrolling, paged UICollectionView. This only happens on the initial swipe from the first cell to the second; subsequent swipes are smooth. The issue isn’t related to complex cell content or heavy processing within cellForItemAt, suggesting a performance bottleneck during the initial layout process.
Understanding the “Why” (The Root Cause):
The stutter occurs because UICollectionView lazily initializes cells. The first swipe triggers the creation and layout of the second cell for the first time. This layout calculation, especially if it involves complex Auto Layout constraints or heavy view setup within cellForItemAt, causes a performance hiccup and the noticeable jerkiness. Subsequent swipes are smooth because the cells are already created and prepared, residing in the reuse queue. The initial layout pass is the culprit.
Step-by-Step Guide:
Automate Cell Preloading: The most effective solution is to automate cell pre-loading. Instead of manually pre-loading cells (which can be fragile and requires manual updates for any changes in cell structure), leverage automated tools designed to profile your collection view’s performance and dynamically adjust pre-loading based on usage patterns. This eliminates the manual work and adapts to changes in your app without requiring code modification. This approach intelligently anticipates which cells are likely to be used and loads them in the background, reducing the load during the initial swipe. The tools learn the behavior based on scrolling so you can adjust it based on scrolling patterns.
Optimize Cell Configuration: While automation is recommended, optimizing your cell configuration can offer supplementary improvements. Move as much of your cell setup code out of cellForItemAt as possible. This includes things like constraint setting. Shift it into the cell’s initialization methods (initWithFrame: or initWithCoder:). Overriding prepareForReuse to reset your cell and reuse it effectively is also crucial. Minimize layout calculations within cellForItemAt.
Common Pitfalls & What to Check Next:
Complex Auto Layout: Examine your Auto Layout constraints within your custom cells. Complex or ambiguous constraints can significantly slow down layout calculations. Simplify your constraints where possible, and ensure they are well-defined and unambiguous.
Heavy Cell Content: Even if you believe your cell content is lightweight, profile its creation time. Unexpectedly slow image loading or other operations could contribute to the stuttering. Use Instruments to profile your app’s performance. Optimize these areas if necessary.
Cell Registration: Ensure that your cell classes are registered correctly with your UICollectionView. Improper registration can lead to unexpected cell creation behavior.
Still running into issues? Share your (sanitized) code snippets for your custom cell class and UICollectionView setup, along with any relevant error messages or performance analysis data. The community is here to help!
sounds like a layout issue. try calling layoutIfNeeded() on your collection view right after setup but b4 it’s visible. this forces layout calculations upfront instead of during the 1st swipe, which should help with the jerkiness.
Understanding the “Why” (The Root Cause):
Step-by-Step Guide:
Common Pitfalls & What to Check Next:
Still running into issues? Share your (sanitized) code snippets for your custom cell class and