# CFURLCreateStringByReplacingPercentEscapes(_:_:_:) Creates a new string by replacing any percent escape sequences with their character equivalent. ``` func CFURLCreateStringByReplacingPercentEscapes(_ allocator: CFAllocator!, _ originalString: CFString!, _ charactersToLeaveEscaped: CFString!) -> CFString! ``` ## Parameters `allocator` The allocator to use to allocate memory for the new `CFString` object. Pass `NULL` or [`kCFAllocatorDefault`](/documentation/CoreFoundation/kCFAllocatorDefault) to use the current default allocator. `originalString` The `CFString` object to be copied and modified. `charactersToLeaveEscaped` Characters whose percent escape sequences, such as `%20` for a space character, you want to leave intact. Pass `NULL` to specify that no percent escapes be replaced, or the empty string (`CFSTR("")`) to specify that all be replaced. ## Return Value A new `CFString` object, or `NULL` if the percent escapes cannot be converted to characters, assuming UTF-8 encoding. If no characters need to be replaced, this function returns the original string with its reference count incremented. Ownership follows the create rule. See [The Create Rule](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFMemoryMgmt/Concepts/Ownership.html#//apple_ref/doc/uid/20001148-103029). ## Discussion --- 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)