what does Error “Thread 1:EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)” mean?

Question

I got this error:

Thread 1:EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)

How can I solve this? The code works normally,

Answer 1

I got this error while I tried to write to a variable at the same time from different threads. Creating a private queue and making sure one thread at a time can write to that variabele at the same time. It was a dictionary in my case.