Method to iterate the properties on an object

objc+blocks.h

/*
 *  objc+blocks.h
 *
 *  Created by Kevin Ballard on 1/13/10.
 *
 */

#import <objc/runtime.h>

enum {
	PropertyIteratorFlagReadonly    = (1 << 0),
	PropertyIteratorFlagCopy        = (1 << 1),
	PropertyIteratorFlagRetain      = (1 << 2),
	PropertyIteratorFlagNonatomic   = (1 << 3),
	PropertyIteratorFlagDynamic     = (1 << 4),
	PropertyIteratorFlagWeak        = (1 << 5),
	PropertyIteratorFlagCollectable = (1 << 6),
};
typedef NSUInteger PropertyIteratorFlags;

typedef struct PropertyIteratorInfo {
	NSString *name;
	PropertyIteratorFlags flags;
	NSString *typeEncoding;
	SEL getter;
	SEL setter;
	NSString *ivar;
} PropertyIteratorInfo;

void objc_iterateProperties(id obj, void (^iterator)(PropertyIteratorInfo info));

objc+blocks.m

/*
 *  objc+blocks.m
 *
 *  Created by Kevin Ballard on 1/13/10.
 *
 */

#include "objc+blocks.h"

void objc_iterateProperties(id obj, void (^iterator)(PropertyIteratorInfo info)) {
	for (Class klass = [obj class]; klass != [NSObject class]; klass = [klass superclass]) {
		unsigned int pCount;
		objc_property_t *props = class_copyPropertyList(klass, &pCount);
		for (unsigned int i = 0; i < pCount; i++) {
			NSString *attrs = [NSString stringWithUTF8String:property_getAttributes(props[i])];
			NSArray *comps = [attrs componentsSeparatedByString:@","];
			PropertyIteratorInfo info = {0};
			info.name = [NSString stringWithUTF8String:property_getName(props[i])];
			for (NSString *comp in comps) {
				unichar c = [comp characterAtIndex:0];
				comp = [comp substringFromIndex:1];
				switch (c) {
					case 'T': // property type
						info.typeEncoding = comp;
						break;
					case 'R': // readonly
						info.flags |= PropertyIteratorFlagReadonly;
						break;
					case 'C': // copy
						info.flags |= PropertyIteratorFlagCopy;
						break;
					case '&': // retain
						info.flags |= PropertyIteratorFlagRetain;
						break;
					case 'N': // nonatomic
						info.flags |= PropertyIteratorFlagNonatomic;
						break;
					case 'G': // getter
						info.getter = NSSelectorFromString(comp);
						break;
					case 'S': // setter
						info.setter = NSSelectorFromString(comp);
						break;
					case 'D': // dynamic
						info.flags |= PropertyIteratorFlagDynamic;
						break;
					case 'W': // weak
						info.flags |= PropertyIteratorFlagWeak;
						break;
					case 'P': // eligible for garbage collection
						info.flags |= PropertyIteratorFlagCollectable;
						break;
					case 't': // old-style type encoding; ignore this
						break;
					case 'V': // backing ivar name
						info.ivar = comp;
						break;
				}
			}
			if (info.setter == NULL && !(info.flags & PropertyIteratorFlagReadonly)) {
				info.setter = NSSelectorFromString([@"set" stringByAppendingString:[info.name capitalizedString]]);
			}
			if (info.getter == NULL) {
				info.getter = NSSelectorFromString(info.name);
			}
			iterator(info);
		}
		free(props);
	}
}