Question

I released the first beta version of my iPhone app on TestFlightApp today. Everything is going really well until I notice that the responsiveness of the application is pretty cruddy. Certainly doesn’t have a “nice” native feel that I’m going for.

I’ve been particularly fastidious concerning my memory allocation/deallocation, so I don’t think this is the issue. Basically, I don’t know where to turn to next in order to improve the performance of my app.

Here’s where I think some of my slowdown can be attributed to:

1. Using UIAppearance to customize the looks of most (if not all) UI elements. I use a brand new font, lots of CAGradientLayers, and lots of edits to CALayer in order to draw nice Shadows.

2. Grouped UITableViewCells that display pictures of a map and itemized lists.

3. UITableViewCells whose layouts are updated every time I call layoutSubviews.

4. UITableViewCells with customized heights. For each call of heightForRowAtIndexPath, I need to reconstruct and re-layout the view, returning the exact height each time.

5. Because I programmatically created views, controllers with longer viewDidLoad calls tend to load slower. What code can I offset in the init call?

Does anyone have any hints or tips for dealing with these problems? Or perhaps people have stories about how they dealt with a slowdown in performance when they released their first app?

Answer 1

My answer won’t address all of your points, but here are a couple:

1) Make sure you are using Shadow Paths. Paths are much, much more performant.

2) Are you using transparency or corner rounding? If so, try and reduce transparency as much as possible and do not round corners using CALayer cornerRadius. Instead, use a clipping mask in the drawRect of the view that needs to be rounded.

4) Perhaps you can cache the height in an array and not have to repeat the calculation, each and every time. This may/may not scale well depending on the potential number of items, but may be acceptable depending on the use case.

5) Are there views you can reuse? For example, when I have a custom selection view on a UITableViewCell, I only create a single instance held by the controller and reference it in all the cells.