value assigned to a property in the model class disappears in the view/controller class

Question

Right before my model class sends the variable stringToDisplay, NSLog shows me that it has a value. But when I try to use it in my ViewController, I just get

Answer 1

It really depends how you set stringForDisplay inside the performOperation:withArray: method.

for a blind guess, try using

NSString *otherString = self.brain.stringForDisplay;

after this line

double result = [self.brain performOperation:operation withArray:[self.brain whatHappenedSinceLastClear]];