Question

I have this instance method that returns a list of distinct values.

-(void)test
{
  return [self valueForKeyPath:@"@distinctUnionOfObjects.values"];
}

It works for one especific object, but i have a lot of objects.

I am thinking about a class method that returns something like

SELECT DISTINCT column_name(s) FROM table_name

What is the best way to do this? And how can i have do it whith a class method?

Edit:

It works now! Thanks, AKV!

@interface

+(NSArray *)fetchAll; // array with all managed objects.
+(NSSet *)myMethod;

@implementation

+(NSSet *)myMethod
{
    return [NSSet setWithArray:[[MyClass fetchAll] valueForKey:@"myField"]];
}

Answer 1

Create a set, and find the distinct values as :

NSSet *distinctValues = [NSSet setWithArray:[myArrayOfCustomObjects valueForKey:@"yourKey"]];