# method_getArgumentType(_:_:_:_:) Returns by reference a string describing a single parameter type of a method. ``` func method_getArgumentType(_ m: Method, _ index: UInt32, _ dst: UnsafeMutablePointer?, _ dst_len: Int) ``` ## Discussion The parameter type string is copied to `dst`. `dst` is filled as if `strncpy(dst, parameter_type, dst_len)` were called. If the method contains no parameter with that index, `dst` is filled as if `strncpy(dst, "", dst_len)` were called. --- 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)