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objective-cnsarraynspredicatekvc

Distinct Object using NSPredicate

I have an NSArray of custom objects. Consider that the custom objects have a PageNumber property. I would like to filter my NSArray with a condition like "customObject.PageNumber is distinct".

I know I can loop through the array and eliminate object with duplicate pageNumbers. But is there any easy way to do it? I have tried,

[myarray valueForKeyPath:@"distinctUnionOfObjects.pageNumber"];

It is giving me the unique page numbers (like 7, 8, 9). But I want the custom object itself rather than just page numbers. Can any predicate help me?

Solution

  • I have created a simple library, called Linq to ObjectiveC, which is a collection of methods that makes this kind of problem much easier to solve. In your case you need the Linq-to-ObjectiveC distinct method:

    NSArray* itemsWithUniquePageNumbers = [items distinct:^id(id item) {
    return [item pageNumber];
}];

    This returns an array of objects, each one with a unique page number.