A workaround for the "yield return www" hang on iOS

Hey,

Today I have encountered a serious issue with Unity and the WWW class (using 5.1.2p3)

In case there's no network connectivity, the following code hangs:

Code (CSharp):

1. yield return www; // hangs !!!

This occurs on iOS only AFAIK.

Here's a post on my blog with a simple workaround (until there's a fix in the next patch release): www.tallior.com/workaround-for-www-yield-bug/

 

Hey @liortal

I can see this bug also in 5.2.0f3. Do you have made a bugreport already for this one?

 

Are you sure ?

This is said to be resolved in 5.1.2p3 . maybe these changes are not rolled into 5.2 yet ?

 

Well, not 100% sure that it is this problem, but the following code will never hit the last debug output on 5.2.0f1, but on 5.1.2f1:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class downloader : MonoBehaviour {
5.  
6.     private IEnumerator startDownload(WWW aDownload)
7.     {
8.         var sec = 0f;
9.         Debug.Log("start download");
10.  
11.         Debug.Log(aDownload.isDone);
12.  
13.         while (!aDownload.isDone && sec < 10f)
14.         {
15.             sec += Time.deltaTime;
16.             Debug.Log(aDownload.isDone + " Caching: " + Caching.ready);
17.  
18.             yield return aDownload;
19.         }
20.  
21.  
22.         if (sec >= 10f) {
23.             Debug.Log("security timeout");
24.         }
25.  
26.         yield return aDownload;
27.  
28.         Debug.Log("download ended: " + aDownload.error + ". sec: " + sec + ". Caching: " +  Caching.ready);
29.     }
30.  
31.     // Update is called once per frame
32.     void OnGUI ()
33.     {
34.  
35.         if (GUI.Button (new Rect(100, 100, 100, 100), "start"))
36.         {
37.             StartCoroutine(startDownload(new WWW("http://www.noexistant.com/myAsset.asset")));
38.         }
39.     }
40. }
41.  

Now I've got the test project (which took me 30 minutes, while finding that it is something here took me a few days ) and I can create a bug report for Unity.


Update: Case 727455

 

This looks pretty similar to my issue. That was fixed for 5.1.2p3 so maybe it will be merged into 5.2 in the first patch that will be released...

Have you tried the code i posted as a workaround ?

 

Yes, I tried that and it worked for the yield return aDownload. But then the Caching.ready is always false, which I need for the assetbundles. The code is working in 5.1.2f1, but not in 5.2.

 

if the download fails, Caching.ready should return false right? isn't this the case here ?

 

Caching.ready only shows if caching of assetbundles is possible at all. So, if it's not, WWW.LoadFromCacheOrDownload will always download the assetbundles new. That's not the behaviour I want to have for my 20 mb assetbundles ^^ For smaller packages it could work, but this function has the intention to work with the caching.

 

Update on this: the fix should be in 5.2.0p1. The QA tested it with the test project and it didn't appear there again. So just wait for the patch release.

 

Any idea how long these patches usually take? I am experiencing the same issue and my game relies on having an internet connection so I really need this update.

At what point are these patch releases considered to be a normal version that will work with the web player?

Thanks

Mat

 

Patches come out usually around once a week or so. Not sure how it'll go with the newly released version (5.2).

 

The 5.2.0p1 should come this week, but don't nail me on that

 

5.2.0p1 is out now, so this should solve the issue, in case you've been waiting for it

 

5.2.0p1 is out now with the fix

 

This still happens to me on Unity 5.2.4

 

On galaxy tab s7