Get NSIndexSet from NSArray

Question

NSArray has useful methods to find objects for specified indexes

// To find objects by indexes
- (id)objectAtIndex:(NSUInteger)index
- (NSArray *)objectsAtIn         


        

Answer 1

Newer NSArray versions (OSX 10.6 and iOS 4) provides the indexesOfObjectsPassingTest: method.

NSIndexSet *indexesOfObjects = [[array1 indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
    return [array2 containsObject:obj];
}];