# replaceSubrange(_:with:) Replaces a range of elements with the elements in the specified collection. ``` mutating func replaceSubrange(_ subrange: Range, with newElements: C) where Element == C.Element, C : Collection ``` ## Parameters `subrange` The subrange of the array to replace. The start and end of a subrange must be valid indices of the array. `newElements` The new elements to add to the array. ## Discussion This method has the effect of removing the specified range of elements from the array and inserting the new elements at the same location. The number of new elements need not match the number of elements being removed. In this example, three elements in the middle of an array of integers are replaced by the five elements of a `Repeated` instance. ``` var nums = [10, 20, 30, 40, 50] nums.replaceSubrange(1...3, with: repeatElement(1, count: 5)) print(nums) // Prints "[10, 1, 1, 1, 1, 1, 50]" ``` If you pass a zero-length range as the `subrange` parameter, this method inserts the elements of `newElements` at `subrange.startIndex`. Calling the `insert(contentsOf:at:)` method instead is preferred. Likewise, if you pass a zero-length collection as the `newElements` parameter, this method removes the elements in the given subrange without replacement. Calling the `removeSubrange(_:)` method instead is preferred. > Complexity: O(*n* + *m*), where *n* is length of the array and > *m* is the length of `newElements`. If the call to this method simply > appends the contents of `newElements` to the array, this method is > equivalent to `append(contentsOf:)`. --- 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)