Question

Why does this syntax work

   NSString* newDisplayText = [currentDisplayText stringByAppendingString:digit];

while this one, (assigning the digit NSStrin to the new string first, and then sending it a message using the stringByAppendingString method). Does not work?

  NSString* newDisplayText = digit;
  [newDisplayText stringByAppendingString:currentDisplayText];

does sending it this method override it´s previous value I set?

Answer 1

I’m having a really hard time figuring out exactly what you’re asking, but here’s a try:

The method -stringByAppendingString: does not modify its receiver. It constructs a new NSString* object and returns that. So saying

[newDisplayText stringByAppendingString:currentDisplayText];

does absolutely nothing, since you’re throwing away the newly-created string.