Question

This is what is returning the error:

NSMutableArray *newArray = [[[NSMutableArray alloc] initWithArray:[NSJSONSerialization JSONObjectWithData:[[[appDelegate.Matches objectAtIndex:(NSUInteger)indexPath] objectForKey:@"chat"] dataUsingEncoding:NSUTF8StringEncoding] options:NSJSONReadingMutableContainers error:nil]] addObject:[NSDictionary dictionaryWithObjectsAndKeys:message, @"message", [NSString stringWithFormat:@"%llu", appDelegate.userId], @"id", nil]];

Answer 1

“Holy run-on expression, Batman!”

If you were to separate that out into multiple lines, you could easily see where the problem is.

Or, more likely, the error would mysteriously go away.

The problem is that addObject: returns (void), but you are trying to assign the return value of that method to the variable.