Remove Emoji from nickname before joining a room

[Bcow7]

As reported in the issue #879, it isn’t possible to join a MUC with a
nickname that contains some Emojis.
Quick fix that prevent failure.

[chrisballinger]

Are you using the latest version of KissXML? Issues with encoding UTF-8 / emoji were fixed a few months ago, but perhaps there are other areas that we missed. robbiehanson/KissXML#36

I'm not sure if stripping certain unicode values in XMPPFramework is the right approach if it's technically valid and accepted by some(?) servers.

[Bcow7]

I'm using KissXML (5.1.2) and XMPPFramework (3.7.0)

I know that unicode are accepted by servers into messages, but I was ignoring that we can use them inside nicknames...so maybe you're right and it is better to keep the framework like it is...

[Bcow7]

But maybe we could trigger an error when the library fails to join the MUC in this case, what do you think?

[chrisballinger]

@Bcow7 That would make sense, but I'm not familiar enough with the MUC spec to know how to properly catch the error. Here's where we handle successful joins:

https://github.com/robbiehanson/XMPPFramework/blob/master/Extensions/XEP-0045/XMPPRoom.m#L1051

I'm guessing you could add XMPPIDTracker to - (void)joinRoomUsingNickname:(NSString *)desiredNickname history:(NSXMLElement *)history password:(NSString *)passwd and look for errors:

https://github.com/robbiehanson/XMPPFramework/blob/master/Extensions/XEP-0045/XMPPRoom.m#L265