Fooling around with the ObjC Runtime

EasyArchives.m

@interface ArchivesEasy: NSObject <NSCoding>
@end

@implementation ArchivesEasy

-(id)initWithCoder:(NSCoder *)aDecoder
{
    if (self = [super init]) {
        [self enumeratePropertiesWithBlock:^(NSString *key, id value) {
            [self setValue:[aDecoder decodeObjectForKey:key] forKey:key];
        }];
    }
    
    return self;
}

-(void)encodeWithCoder:(NSCoder *)aCoder
{
    [self enumeratePropertiesWithBlock:^(NSString *key, id val) {
        [aCoder encodeObject:val forKey:key];
        NSLog(@"Encoded value %@ for key %@", val, key);
    }];
}

-(void)enumeratePropertiesWithBlock:(void (^)(NSString*, id))block
{
    unsigned int count;
    objc_property_t* properties = class_copyPropertyList([self class], &count);
    for (int i = 0; i < count; i++) {
        objc_property_t property = properties[i];
        NSString* propertyKey = [NSString stringWithCString:property_getName(property)
                                                   encoding:NSUTF8StringEncoding];
        id value = [self valueForKey:propertyKey];
        block(propertyKey, value);
    }
}

@end

// Put this in +load of a target class.
BOOL mixin(Class mixer, Class target) {
    unsigned int count;
    Method* methods = class_copyMethodList(mixer, &count);
    BOOL allSucceeded = YES;
    for (int i = 0; i < count; i++) {
        Method m = methods[i];
        SEL selector = method_getName(m);
        IMP implementation = method_getImplementation(m);
        const char* encoding = method_getTypeEncoding(m);
        allSucceeded = allSucceeded && class_addMethod(target, selector, implementation, encoding);
    }
    return allSucceeded;
}