Question

I have been working with NSArrays and NSMutableArrays that store NSDate objects for a few days now. I noticed that calling [listOfDates removeObject:date1] removes all the NSDate objects from the array. I have instead been doing this to remove objects:

  NSMutableArray *dateList; // Has Dates in it
  NSDate *dateToRemove;     // Date Object to Remove
  __block NSUInteger indexToRemove;
  __block BOOL       foundMatch = NO;
  [dateList enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
    if ([obj isEqualToDate:dateToRemove]) {
      indexToRemove = idx;
      foundMatch = YES;
      *stop = YES;
     }
  }];
  if (foundMatch) {
    [dateList removeObjectAtIndex:indexToRemove];
  }

Is there a better way to be doing this? Perhaps another data structure? Or a simpler function?

Answer 1

You should use the first method you tried:

[listOfDates removeObject:date1];

This will remove date1 and ONLY date1 from listOfDates. This should NOT remove all NSDate objects from listOfDates unless all NSDate objects in listOfDates are date1.

You could also use removeObjectAtIndex: combined with indexOfObject: to product the same effect, but that’s extra code.

From the NSMutableArray class reference for removeObject:

This method uses indexOfObject: to locate matches and then removes
them by using removeObjectAtIndex:. Thus, matches are determined on
the basis of an object’s response to the isEqual: message. If the
array does not contain anObject, the method has no effect (although it
does incur the overhead of searching the contents).