Wikitude

App crashes on leaving ARViewController with a marker being tracked[URGENT]

Hi,

I've implemented the Wikitude SDK + Studio inside our app, but I found a problem:

if I'm tracking a marker and I leave the ARViewController (for example I go back to the app Home Screen) the app crashes throwing the following error:
 

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-: unrecognized selector sent to instance 0xd000000013e0911b'

*** First throw call stack:

(0x18609cf48 0x19ac4ff80 0x1860a3c5c 0x1860a0c00 0x185fa4cac 0x100171c3c 0x100cedca8 0x100cedc68 0x100cf3710 0x1860541f8 0x186052060 0x185f80ca0 0x1911bc088 0x18b698ffc 0x10015e374 0x19b49e8b8)

 

This happens only if i'm tracking a marker and I leave the ARViewController

Please help me because I need to publish the app but first I need to fix this problem