nsenumerator

I know that if you have a loop that modifies the count of the items in the loop, using the NSEnumerator on a set is the best way to make sure your code blows up, however I would like to understand the performance tradeoffs between the NSEnumerator class and just an old school for loop Using the new for (... in ...) syntax in Objective-C 2.0 is generally the fastest way to iterate over a collection because it can maintain a buffer on the stack and get batches of items into it. Using NSEnumerator is generally the slowest way because it often copies the collection being iterated; for immutable

I have seen this over and over, why exactly is it faster to use fast enumeration in loops rather than an NSEnumerator using nextObject: . Lily Ballard NSEnumerator is the old way to enumerate over collections. It involves creating an object to represent the enumeration, then calling a method on it for every single iteration. While this was perfectly serviceable for many years, it's not terribly efficient, as it involves at least one message send for every iteration of the loop. NSFastEnumeration is the more modern approach, which leverages native language support to provide a much more

I have a Firebase resource that contains several objects and I would like to iterate over them using Swift. What I expected to work is the following (according to the Firebase documentation) https://www.firebase.com/docs/ios-api/Classes/FDataSnapshot.html#//api/name/children var ref = Firebase(url:MY_FIREBASE_URL) ref.observeSingleEventOfType(.Value, withBlock: { snapshot in println(snapshot.childrenCount) // I got the expected number of items for rest in snapshot.children { //ERROR: "NSEnumerator" does not have a member named "Generator" println(rest.value) } }) So it seems there is a problem