nsindexset

I converted an NSIndexSet to an [Int] array using the answer at https://stackoverflow.com/a/28964059/6481734 I need to do essentially the opposite, turning the same kind of array back into an NSIndexSet. Alexander Swift 3 IndexSet can be created directly from an array literal using init(arrayLiteral:) , like so: let indices: IndexSet = [1, 2, 3] Original answer (Swift 2.2) Similar to pbasdf's answer , but uses forEach(_:) let array = [1,2,3,4,5,7,8,10] let indexSet = NSMutableIndexSet() array.forEach(indexSet.add) //Swift 3 //Swift 2.2: array.forEach{indexSet.addIndex($0)} print(indexSet) This

This feels like a dumb question because it seems to me like my use case must be quite common. Say I want to represent a sparse set of indexes with an NSIndexSet (which is of course what it's for). I can use -firstIndex to get the lowest one and -lastIndex for the highest, but what's the canonical way to get a single, arbitrary index in the middle, given its "index"? The docs have left me unclear. E.g. if I have an index set with the indexes { 0, 5, 8, 10, 12, 28 }, and I want to say "give me the fourth index" and I'd expect to get back 10 (or 12 I suppose depending on whether I count the

Can you fast enumerate a NSIndexSet ? if not, what's the best way to enumerate the items in the set? Fast enumeration must yield objects; since an NSIndexSet contains scalar numbers ( NSUInteger s), not objects, no, you cannot fast-enumerate an index set. Hypothetically, it could box them up into NSNumbers, but then it wouldn't be very fast. In OS X 10.6+ and iOS SDK 4.0+, you can use the -enumerateIndexesUsingBlock: message: NSIndexSet *idxSet = ... [idxSet enumerateIndexesUsingBlock:^(NSUInteger idx, BOOL *stop) { //... do something with idx // *stop = YES; to stop iteration early }]; A

I'm getting the select items from a table view with: NSIndexSet *selectedItems = [aTableView selectedRowIndexes]; what's the best way to get the indexes in a NSArray object? Enumerate the set, make NSNumbers out of the indexes, add the NSNumbers to an array. That's how you'd do it. I'm not sure I see the point in transforming a set of indexes into a less efficient representation, though. To enumerate a set, you have two options. If you're targeting OS X 10.6 or iOS 4, you can use enumerateIndexesUsingBlock: . If you're targeting earlier versions, you'll have to get the firstIndex and then keep