# applyTransform(_:reverse:range:updatedRange:) Transliterates the receiver by applying a specified ICU string transform. ``` func applyTransform(_ transform: StringTransform, reverse: Bool, range: NSRange, updatedRange resultingRange: NSRangePointer?) -> Bool ``` ## Parameters `transform` The transformation to apply. For a list of possible values, see [String Transformations](/documentation/Foundation/string-transformations). If the specified transform does not exist, the receiver is not modified, and this method returns . `reverse` Whether an inverse transform should be used. If the specified transform does not have an inverse, the receiver is not modified, and this method returns . `range` The range of the string to transform. `range` must not exceed the bounds of the receiver. > Important: > Raises an `NSRangeException` if any part of `aRange` lies beyond the end of the string. `resultingRange` If the transform was successfully applied, upon return contains the range of the transformed string. ## Return Value if the transform was successfully applied. Otherwise, . ## Discussion In addition to the provided transformation constants, you may use any valid ICU transform ID as defined in the [ICU User Guide](http://userguide.icu-project.org/transforms/general). However, arbitrary ICU transform rules are not supported. --- 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)