Methods in Objective-C have compound names that describe their main name and any arguments. Functions like invoke that need a method name expect a string with all the name components concatenated together with no spaces.
For example, a call in Objective-C such as:
[box setWidth:10 height:20]
would be written using invoke as:
(invoke box "setWidth:height:" 10 20)
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 15 Dec 2011