# next() Advances to the next element and returns it, or `nil` if no next element exists. ``` mutating func next() -> LazyDropWhileSequence.Iterator.Element? ``` ## Return Value The next element in the underlying sequence, if a next element exists; otherwise, `nil`. ## Discussion Repeatedly calling this method returns, in order, all the elements of the underlying sequence. As soon as the sequence has run out of elements, all subsequent calls return `nil`. You must not call this method if any other copy of this iterator has been advanced with a call to its `next()` method. The following example shows how an iterator can be used explicitly to emulate a `for`-`in` loop. First, retrieve a sequence’s iterator, and then call the iterator’s `next()` method until it returns `nil`. ``` let numbers = [2, 3, 5, 7] var numbersIterator = numbers.makeIterator() while let num = numbersIterator.next() { print(num) } // Prints "2" // Prints "3" // Prints "5" // Prints "7" ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)