The equivalent of ‘toString’ in Objective-C.

If you’ve ever wondered if there’s a convenient way in Objective-C to write a function for “expressing” the value of an object of yours, as a string, just like “toString” in e.g. JavaScript (and Java? I think), I’ve got good news:

-(NSString *)description

Add the above method to your Objective-C class and you’ll be able to NSLog it or get its string value anywhere using [OBNAME description]. In short, it will now respond with its ‘description’ to ‘%@’ in an NSString stringWithFormat expression.

Example:

@interface Person : NSObject {
  NSString *name;
  NSString *phone;
  NSInteger age;
}

-(NSString *)description;
[...]
-(NSString *)description
{
  return [NSString stringWithFormat:@"%@ (%d): %@",
        name, age, phone];
}

Then somewhere we have a Person object and we want to see its value.

NSLog(@"We've got %@", aPerson);
myLabel.text = [NSString stringWithFormat:@"Details: %@", aPerson];

(pardon any errors in code above — untested as is)