# CFURLCreateStringByReplacingPercentEscapesUsingEncoding(_:_:_:_:) Creates a new string by replacing any percent escape sequences with their character equivalent. ``` func CFURLCreateStringByReplacingPercentEscapesUsingEncoding(_ allocator: CFAllocator!, _ origString: CFString!, _ charsToLeaveEscaped: CFString!, _ encoding: CFStringEncoding) -> 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. `origString` The `CFString` object to be copied and modified. `charsToLeaveEscaped` 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. `encoding` Specifies the encoding to use when interpreting percent escapes. If you are uncertain of the correct encoding, you should use UTF-8 ([`CFStringBuiltInEncodings.UTF8`](/documentation/CoreFoundation/CFStringBuiltInEncodings/UTF8)), which is the encoding designated by RFC 3986 as the correct encoding for use in URLs. ## Return Value A new `CFString` object, or `NULL` if the percent escapes cannot be converted to characters, assuming the encoding given by `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)