Improving UIWebView initialization time

Question

My company uses a UIWebView to display ads. The issue I'm having is that initializing a UIWebView appears to be expensive; profiling with Time Profiler shows [UIWebView alloc] initWithFrame:CGRectMake(0,0,500,500)] to take 31–40ms. This is enough to cause noticeable frame drops in games running at 60 FPS.

Is there a way to workaround this slow initialization time? My current ideas are to create a UIWebView when the app launches (but before gameplay has started), and reuse that (potentially creating a pool of them to reuse, like how UITableViewCell works) or to try and see if WKWebView has better performance.

Answer 1

Here are my findings:

1. WKWebView does not initialize any faster. Creating WKWebViews took a similar amount of time as creating UIWebViews (in the 1 test I did, it took 46ms to create two WKWebViews.
2. The very first web view created takes significantly longer to create than subsequent web views. The first one takes 31–42 ms; subsequent ones take ~11ms to create. The good news here is that creating the first web view when e.g. the app launches allows future webviews to be created more cheaply, avoiding a 40ms hit while the game is running.
3. Creating a pool of UIWebViews was a good solution for my use case. By creating the webviews at app launch and then reusing them, I avoid causing a frame drop while the game is running.

Answer 2

There is not much difference in the responsiveness between UIWebView and WKWebView because WKWebView has been introduced for a consistency matter between iOS and OSX. The underlying engine is Webkit in either way and it requires a lot of initialization.

The best solution I've found recent during years has been fading a WebView starting from a view with 0.1 alpha in which the url was loaded. Be careful to not start from 0.0 and do not have your webview detached from main view hierarchy because your url would not be loaded.

When didFinishLoading is called then you can fade it to 1.0 thus providing a better user experience. Personally I don't like the UIWebView pool because I have experienced some memory troubles when maintaining it, especially on iOS 7 devices.