Using global variables in Objective-C

Question

First of all, I tried almost all the solutions given in stackoverflow but I didn\'t succeed in implement global vars, I even did a step by step tutorial and still I get the

Answer 1

The error has nothing to do with global variables. The error message

-[__NSArrayM length]: unrecognized selector sent to instance 0x8b7fbc0

indicates that you somewhere in your code assigned a NSMutableArray to farmerCardNumber instead of a NSString.

For example, if you do something like

farmerCardNumber = [someDictionary objectForKey:@"someKey"];

and [someDictionary objectForKey:@"someKey"] happens to be an array and not a string, then farmerCardNumber points to that array, even if it was declared as pointer to a string.