How to show a GIF on iOS in a certain frame, not show it until fully loaded, and allow zoom?

Question

When a user selects a GIF, I want to present an overlay on top of everything showing the GIF.

I know there's a few ways on iOS to do this. There's the great UIImage+animatedGIF which works decently well, but for longer GIFs they're very slow and don't play back at the same speed as a UIWebView would (which plays at the accurate playback speed).

It sucks, because if that category didn't play them back slowly it would do everything I need.

But it doesn't, so I tried with UIWebView, however I'm confused about three things:

1. How do I get size that the UIWebView should be when presented (its frame)? Would I have to download the GIF first as a UIImage then check its size property? Is there a better way (might take awhile)?

2. How do I stop it from playing until it's fully loaded?

3. With the above category, as it's just a UIImage, when I embed it as a UIImageView in a scrollview it's very easy to zoom in and out of. Is this possible with a UIWebview?

Answer 1

1.

The first solution that comes to mind is to set the background of the webview to clear color and place it in the right location after it finishes loaded. Usually I use

[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight;"]

but that won't work if you are directing your webview to a gif url.

2.

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    webView.alpha = 1;
}

That way the UIWebView will be shown to the user only after the gif is full loaded.

3.

[webView setScalesPageToFit:YES];