iOS: UnityWebRequest crash in WWWConnection.mm : WaitOnCondition()

Unity Engine
, ,
1

via testflight beta, we’re seeing an infrequent crash in WWWConnection.mm,
on this line:

static void WaitOnCondition(UnityWWWConnectionDelegate* delegate)
{
    NSCondition *condition = delegate.condition;
    [condition lock];          <-------------------------- crash
    [condition wait];
    [condition unlock];
}

others are seeing this as well:

2

This bug has been fixed and we’re shipping it in patch releases. However, the fix is very trivial and you can do it yourself without risking an upgrade: in the same file find a definition for UnityWWWConnectionDelegate and remove the ‘nonatomic’ flag from the condition property.

3

woohoo!
many thanks Aurimas-Cernius! this is great.

i’ll add this to the “answers” thread as well.

4

Howdy -

this declaration actually occurs in two places:
WWConnection.h and WWConnection.mm both have this line:

@property (readonly, retain, nonatomic) NSURLConnection*    connection;

i assume they should both be modified ?

5

Yes, that is correct, though it seems enough to only modify the .mm file.

6

got it. thanks.

7

We’re having the same problem. But you need to remove nonatomic from NSCondition* condition, not NSURLConnection* connection. And that’s only in WWWConnection.mm.

When can we expect a Unity patch for this? We’re using Cloud Build, which makes it harder to remove the nonatomic.

8

Which release are you using. This fix so far has been backported to 5.6 and newer, patch releases with the fix are not yet out, but are being tested now.

9

Do you have a reliable way to reproduce the problem ?
It’s quite rare for us.

10

We use 5.6.3f1. We might upgrade to 2017 if that one gets the patch first.

Unfortunately, no. It just randomly happens sometimes when I switch view. Our Unity project is more an app than a game. We have to do a bunch of request to retrieve all images and data. Maybe it’s related, but every time we close a view, we do Resources.UnloadUnusedAssets.

11

Looks like 5.6.3p4 has just arrived and should fix this issue :slight_smile:

12

@Aurimas-Cernius Thanks for the solution. Which version of Unity 2017 should we expect the solution in?

13

@GAMEDIA_Justin We’re using the following iOS PostBuild script to replace the overriden files. Just place in the appropriate folder and add a “.override” to the .mm filename. Should work with Cloudbuild.

14

I’m using Unity 2017.2 and I have this issue, crashing for ~8% of the player base.
Looked on WWWConnection.mm and the property is like this, so should be working I guess:

@property (strong, atomic)               NSCondition*          condition;

Anyone know what could be causing it?

edit: added crash log

3421801–270029–Crash March 12.txt (115 KB)

15

The attached pdf file looks blank page to me.

16

@Aurimas-Cernius Sorry about that, updated the file with a .txt version that seems to be working

17

It apparently shouldn’t matter, but what about the same declaration in WWConnection.h ?

18

There is none O.o

3422796--270119--Screen Shot 2018-03-13 at 10.23.10 AM.png

19

From the looks of it I think the WWWConnection gets destroyed before this call. Which version are you on? Looks a pretty old one.

20

@Aurimas-Cernius I’m using Unity 2017.2 and Xcode 9.2