NSObject+CleanUpProperties.m

//
//  NSObject+CleanUpProperties.m
//
//  Created by Vincent Gable on 12/4/08.
//  vincent.gable@gmail.com
//  http://vincentgable.com
//  Copyright 2008 Vincent Gable.
//  You are free to use this code however you like.
//  But I would appreciate hearing what you use it for :-)
//

#import "NSObject+CleanUpProperties.h"


@implementation NSObject(CleanUpProperties)

//syntax is:
//,S(methodNameHere):,
//for example:
//,SintSetFoo:,
//This would be even easier with regex.
//for more information on attribute strings see:
//   http://developer.apple.com/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/chapter_8_section_4.html#//apple_ref/doc/uid/TP40008048-CH101-SW5
static NSString* SetterNameFromAttributes(const char *propertyAttrsCString) {
	NSString *propertyAttributes = [NSString stringWithUTF8String:propertyAttrsCString];
	for(NSString *property in [propertyAttributes componentsSeparatedByString:@","])
		if([property hasPrefix:@"S"] && [property hasSuffix:@":"])
			return [property substringFromIndex:1];		
	
	return nil;
}

static NSString *SetterNameFromPropertyName(const char* propertyNameCStr) {
	NSString *propertyName = [NSString stringWithUTF8String:propertyNameCStr];
	NSString *firstLetterCapitalized = [[propertyName substringToIndex:1] capitalizedString];
	NSString *propertyNameTail = [propertyName substringFromIndex:1];
	return [NSString stringWithFormat:@"set%@%@:",firstLetterCapitalized, propertyNameTail];
}

//for more information on attribute strings see:
//   http://developer.apple.com/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/chapter_8_section_4.html#//apple_ref/doc/uid/TP40008048-CH101-SW5
static BOOL PropertyIsObjCObject(const char* propertyAttributeString) {
	return propertyAttributeString && 
	       propertyAttributeString[0] == 'T' &&
	       propertyAttributeString[1] == '@'; //all other pointers have a '^' here
}

//Readonly properties have
//",R,"
//in their attribute strings
//for more information on attribute strings see:
//   http://developer.apple.com/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/chapter_8_section_4.html#//apple_ref/doc/uid/TP40008048-CH101-SW5
static BOOL PropertyIsSettable(const char* propertyAttributeString) {	
	return NULL == strstr(propertyAttributeString, ",R,");
}

- (void) setEveryObjCObjectPropertyToNil;
{
	unsigned int i, propertyCount = 0;
	objc_property_t *propertyList = class_copyPropertyList([self class], &propertyCount);
	if(propertyList){
		for(i = 0; i < propertyCount; i++){
			const char *propertyAttrs =  property_getAttributes(propertyList[i]);
			if(PropertyIsObjCObject(propertyAttrs) && PropertyIsSettable(propertyAttrs)) {
				NSString *setterName = SetterNameFromAttributes(propertyAttrs);
				if(!setterName)
					setterName = SetterNameFromPropertyName(property_getName(propertyList[i]));
				[self performSelector:NSSelectorFromString(setterName) withObject:nil];
			}
		}
		free(propertyList);
	}
}

@end