Re: How to set value in NSArray

[Richard Frith-Macdonald]

On 13 Jul 2004, at 17:09, Vikram Vyas wrote:

> Hello,
>
> I would like to set value of an NSArray object, monthlyRain, to a 
> particular value
>
> -(void)setMonth:(NSNumber *)month AmountOfRain:(NSNumber *)rain
> {
>     if([monthlyRain objectAtIndex:[month unsignedIntValue]] != rain)
>     {
>         // set monthly value for the month given by the index to the 
> amount
>         // rain
>
>     }
> }
>
> but I cannot find an appropriate method. Would appreciate any help.

You can't ... and NSArray is an immutable object.

What you can do is make a mutable copy of the object and use
the replaceObjectAtIndex:withObject: method of NSMutableArray.

eg.

@interface MyClass : NSObject
{
  NSMutableArray * monthlyRain;
}
- (id) initWithArray: (NSArray*)anArray;
- (void) setMonth: (NSNumber*)month amountOfRain: (NSNumber*)rain;
@end

@implementation MyClass
- (void) dealloc
{
  DESTROY(monthlyRain);
  [super dealloc];
}
- (id) initWithArray: (NSArray*)anArray
{
  monthlyRain = [anArray mutableCopy];
  return self;
}
- (void) setMonth: (NSNumber*)month amountOfRain: (NSNumber*)rain
{
  unsigned index = [month unsignedIntValue];

  if ([[monthlyRain objectAtIndex: index] isEqual: rain] == NO)
    {
      [monthlyRain replaceObjectAtIndex: index withObject: rain];
    }
}