# CFStringFindWithOptions(_:_:_:_:_:) Searches for a substring within a range of the characters represented by a string and, if the substring is found, returns its range within the object’s characters. ``` func CFStringFindWithOptions(_ theString: CFString!, _ stringToFind: CFString!, _ rangeToSearch: CFRange, _ searchOptions: CFStringCompareFlags, _ result: UnsafeMutablePointer!) -> Bool ``` ## Parameters `theString` The string in which to to search for `stringToFind`. `stringToFind` The substring to search for in `theString`. `rangeToSearch` A range of the characters to search in `theString`. The specified range must not exceed the length of the string. `searchOptions` The option flags to control the search behavior. See [String Comparison Flags](/documentation/CoreFoundation/string-comparison-flags) for possible values. The flags [`compareNumerically`](/documentation/CoreFoundation/CFStringCompareFlags/compareNumerically) and [`compareForcedOrdering`](/documentation/CoreFoundation/CFStringCompareFlags/compareForcedOrdering) are ignored. `result` On return, if the function result is `true`, contains the starting location and length of the found substring. You may pass `NULL` if you only want to know if the substring exists in the larger string. ## Return Value `true` if the substring was found, `false` otherwise. ## Discussion This function allows you to search only part of the characters of a string for a substring. It returns the found range indirectly, in the final `result` parameter. If you want to know if the entire range of characters represented by a string contains a particular substring, you can use the convenience function [`CFStringFind(_:_:_:)`](/documentation/CoreFoundation/CFStringFind(_:_:_:)). Both of these functions return upon finding the first occurrence of the substring, so if you want to find out about multiple occurrences, call the [`CFStringCreateArrayWithFindResults(_:_:_:_:_:)`](/documentation/CoreFoundation/CFStringCreateArrayWithFindResults(_:_:_:_:_:)) function. Depending on the comparison-option flags specified, the length of the resulting range might be different than the length of the search string. --- 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)