I've been plaing with 'objc_runtime' this weekend, and wanted to show how I created a subclass of NSObject with methods, property, and iVar.
Idea came from this`StackOverflow post <https://stackoverflow.com/questions/7819092/how-can-i-add-properties-to-an-object-at-runtime/7834787#7834787>` import objc_runtime import darwin / foundation from math import log2 type propertyArray = array[3, objc_property_attribute_t] var prop_type = objc_property_attribute_t(name: "T", value: "@\"NSString\"") ownership = objc_property_attribute_t(name: "C", value: "") backingivar = objc_property_attribute_t(name: "V",value: "_privateName") let attrs:propertyArray = [prop_type, ownership, backingivar] objcr: # ********************************************** # ***** DYNAMIC CLASS CREATION BEGINS HERE ***** # ********************************************** proc nameGetter(self: ID, cmd: SEL ): NSString = var ivar = getIvar(cast[Class]([SomeClass class]), "_privateName") result = cast[NSString](getIvar(self, ivar)) proc nameSetter(self: ID, cmd: SEL, newName: NSString ) = var ivar = getIvar(cast[Class]([SomeClass class]), "_privateName") setIvar(self, ivar, [newName.ID copy]) # ***************************** # ***** SUBCLASS NSOBJECT ***** # ***************************** let SomeClass = allocateClassPair(getClass("NSObject"),"SomeClass",0) # ******************************************************************* # ***** ivars can only be added PRIOR to registering the class! ***** # ******************************************************************* discard addIvar(SomeClass,"_privateName",sizeof(ID),log2(sizeof(ID).float).int,"@") # ***************************** # ***** REGISTER SUBCLASS ***** # ***************************** registerClassPair(SomeClass) # ***************************************************************************** # ***** Properties/Methods can only be added AFTER registering the class! ***** # ***************************************************************************** discard addProperty(cast[Class]([SomeClass class]), "name", attrs) discard addMethod(getClass("SomeClass"),registerName("name"), cast[IMP](nameGetter), "@@:") discard addMethod(getClass("SomeClass"),registerName("setName:"), cast[IMP](nameSetter), "v@:@") # ******************************************** # ***** DYNAMIC CLASS CREATION ENDS HERE ***** # ******************************************** proc main() = var o = [SomeClass new] [o setName: @"Steve"] NSLog("%@",[o name]) [o setName: @"Jobs"] NSLog("%@",[o name]) if isMainModule: main() Run AIR.
