define-objc-method (name result-type [result-style])
(object-argspec argspec*) form*
A string naming the method to define.
An Objective-C FLI type.
An optional keyword specifying the result conversion style, either :lisp or :foreign, or a symbol naming a variable.
A symbol naming a variable.
A symbol naming a class defined with define-objc-class.
An optional symbol naming a variable.
A symbol naming a variable.
An Objective-C FLI type.
An optional symbol or list specifying the argument conversion style.
A form.
The macro define-objc-method defines the Objective-C instance method name for the Objective-C classes associated with class-name. The name should be a concatenation of the message name and its argument names, including the colons, for example "setWidth:height:".
If the define-objc-class definition of class-name specifies the (:objc-class-name objc-class-name) option, then the method is added to the Objective-C class objc-class-name. Otherwise, the method is added to the Objective-C class of every subclass of class-name that specifies the :objc-class-name option, allowing a mixin class to define methods that become part of the implementation of its subclasses (see Abstract classes).
When the method is invoked, each form is evaluated in sequence with object-var bound to the object of type class-name associated with the receiver, pointer-var (if specified) bound to the receiver foreign pointer and each arg-var bound to the corresponding method argument.
Each argument has an arg-type (its Objective-C FLI type) and an optional arg-style, which specifies how the FLI value is converted to a Lisp value. If the arg-style is :foreign, then the arg-var is bound to the FLI value of the argument (typically an integer or foreign pointer). Otherwise, the arg-var is bound to a value converted according to the arg-type:
If arg-style is omitted or :lisp then the rectangle is converted to a vector of four elements of the form #(x y width height). Otherwise the argument is a foreign pointer to a ns-rect object.
If arg-style is omitted or :lisp then the size is converted to a vector of two elements of the form #(width height). Otherwise the argument is a foreign pointer to a ns-size object.
If arg-style is omitted or :lisp then the point is converted to a vector of two elements of the form #(x y). Otherwise the argument is a foreign pointer to a ns-point object.
If arg-style is omitted or :lisp then the range is converted to a cons of the form (location . length). Otherwise the argument is a foreign pointer to a ns-range object.
If arg-style is the symbol string then the argument is assumed to be a pointer to an Objective-C NSString object and is converted to a Lisp string or nil for a null pointer.
If arg-style is the symbol array then the argument is assumed to be a pointer to an Objective-C NSArray object and is converted to a Lisp vector or nil for a null pointer.
If arg-style is the a list of the form (array elt-arg-style) then the argument is assumed to be a pointer to an Objective-C NSArray object and is recursively converted to a Lisp vector using elt-arg-style for the elements or nil for a null pointer.
Otherwise, the argument remains as a foreign pointer to the Objective-C object.
If arg-style is the symbol string then the argument is assumed to be a pointer to a foreign string and is converted to a Lisp string or nil for a null pointer.
After the last form has been evaluated, its value is converted to result-type according to result-style and becomes the result of the method.
If result-style is a non-keyword symbol and the result-type is a foreign structure type defined with define-objc-struct then the variable named by result-style is bound to a pointer to a foreign object of type result-type while the forms are evaluated. The forms must set the slots in this foreign object to specify the result.
If result-style is :foreign then the value is assumed to be suitable for conversion to result-type using the normal FLI rules.
If result-style is :lisp then additional conversions are performed for specific values of result-type:
If the value is a vector of four elements of the form #(x y width height), the x, y, width and height are used to form the returned rectangle. Otherwise it is assumed to be a foreign pointer to a ns-rect and is copied.
If the value is a vector of two elements of the form #(width height), the width and height are used to form the returned size. Otherwise it is assumed to be a foreign pointer to a ns-size and is copied.
If the value is a vector of two elements of the form #(x y), the x and y are used to form the returned point. Otherwise it is assumed to be a foreign pointer to a ns-point and is copied.
If the value is a cons of the form (location . length), the location and length are used to form the returned range. Otherwise it is assumed to be a foreign pointer to a ns-range object and is copied.
(:signed :char) or (:unsigned :char)
If the value is nil then NO is returned.If the value is t then YES is returned. Otherwise the value must be an appropriate integer for result-type.
If the value is a string then it is converted to a newly allocated Objective-C NSString object which the caller is expected to release.
If the value is a vector then it is recursively converted to a newly allocated Objective-C NSArray object which the caller is expected to release.
If the value is nil then a null pointer is returned.
Otherwise the value should be a foreign pointer to an Objective-C object of the appropriate class.
The value is coerced to a Objective-C class pointer as if by coerce-to-objc-class. In particular, this allows strings to be returned.
The forms can use functions such as invoke to invoke other methods on the pointer-var. The macro current-super can be used to obtain an object that allows methods in the superclass to be invoked (like super in Objective-C).
See Defining Objective-C methods
See Invoking methods in the superclass
See Abstract classes
LispWorks Objective-C and Cocoa Interface User Guide and Reference Manual - 21 Mar 2017