1.3.3 Special argument and result conversion

LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual > 1 Introduction to the Objective-C Interface > 1.3 Invoking Objective-C methods

1.3.3 Special argument and result conversion

Since the LispWorks Objective-C interface is an extension of the FLI, most conversion of arguments and results is handled as specified in the LispWorks Foreign Language Interface User Guide and Reference Manual . There are a few exceptions to make it easier to invoke methods with certain commonly used Objective-C classes and structures as shown in the Special argument and result conversion for invoke. See the specification of invoke for full details.

Special argument and result conversion for `invoke`
Type	Special argument behavior	Special result behavior
`NSRect`	Allows a vector to be passed.	Converts to a vector.
`NSPoint`	Allows a vector to be passed.	Converts to a vector.
`NSSize`	Allows a vector to be passed.	Converts to a vector.
`NSRange`	Allow a cons to be passed.	Converts to a cons.
`BOOL`	Allow `nil` or `t` to be passed.	None. See Invoking a method that returns a boolean.
`id`	Depending on the Objective-C class, allows automatic conversion of strings and arrays.	None. See Invoking a method that returns a string or array.
`Class`	Allows a string to be passed.	None.
`char *`	Allows a string to be passed.	Converts to a string.

LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 22 Dec 2009