Question

Merry Christmas everybody 🙂

I have a pointer problem. Although I´m familiar with pointer concepts I haven´t used pointers in Objective-C so far the way it´s described here.

I modified it like this:

  int countSInteger = 10;

  [self setHMSValues:countSInteger];

- (void) setHMSValues: (int*) timeCat {
  *timeCat = *timeCat - 1;
}

But now I´receiving a EXC_BAD_ACCESS:

Any Santa hints?

Greetings from Switzerland, Ronald Hofmann

Answer 1

It looks like you want setHMSValues: to calculate and return a value for the integer parameter. However, the parameter is a pointer to an int (int *), and you’re passing a plain int with the value of 10. Because pointers are just integer values themselves (with the integer value representing a memory address), the code is trying to set the value at memory location 10; hence, you get a “bad access” error because your program cannot access or change values at memory location 10.

What you should do is pass the address of countSInteger to the method:

[self setHMSValues:&countSInteger];

However, there’s a better way to do this. Since you’re returning only one value from the method, there’s no need for an out parameter. You can change your method to this:

- (int) setHMSValues: (int) timeCat {
  return timeCat - 1;
}

and call it like this:

int countSInteger = 10;

countSInteger = [self setHMSValues:countSInteger];