Synthesizing properties in Objective-C categories (simple version)

_JEAssociatedObjectsWeakWrapper.h

//
//  _JEAssociatedObjectsWeakWrapper.h
//  JEToolkit
//
//  Created by John Rommel Estropia on 2013/12/14.
//  Copyright (c) 2013 John Rommel Estropia. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface _JEAssociatedObjectsWeakWrapper : NSObject

@property (nonatomic, weak, readonly) id weakObject;

- (id)initWithWeakObject:(id)weakObject;

@end

_JEAssociatedObjectsWeakWrapper.m

//
//  _JEAssociatedObjectsWeakWrapper.m
//  JEToolkit
//
//  Created by John Rommel Estropia on 2013/12/14.
//  Copyright (c) 2013 John Rommel Estropia. All rights reserved.
//

#import "_JEAssociatedObjectsWeakWrapper.h"

@implementation _JEAssociatedObjectsWeakWrapper

- (id)initWithWeakObject:(id)weakObject
{
    self = [super init];
    if (!self)
    {
        return nil;
    }
    
    _weakObject = weakObject;
    return self;
}

@end

JEAssociatedObjects.h

//
//  JEAssociatedObjects.h
//  JEToolkit
//
//  Created by John Rommel Estropia on 2013/10/26.
//  Copyright (c) 2013 John Rommel Estropia. All rights reserved.
//

#import <objc/runtime.h>

#import "_JEAssociatedObjectsWeakWrapper.h"

#ifndef JEToolkit_JEAssociatedObjects_h
#define JEToolkit_JEAssociatedObjects_h

/*! A macro that implements the accessor and mutator methods specified.
 Usage:
 
 JESynthesize(assign, NSInteger, index, setIndex);
 JESynthesize(strong, NSString *, name, setName);
 JESynthesize(copy, void(^)(void), completion, setCompletion);
 JESynthesize(unsafe_unretained, id, unsafeObject, setUnsafeObject);
 JESynthesize(weak, id<UITableViewDelegate>, delegate, setDelegate);
 JESynthesize(strong, NSString *, readonlyID, changeReadonlyID);
 */
#define JESynthesize(ownership, type, getter, setter) \
    static const void *_JESynthesizeKey_##getter = &_JESynthesizeKey_##getter; \
    \
    - (type)getter \
    { \
        return _JESynthesize_get_##ownership(type, getter); \
    } \
    \
    - (void)setter:(type)getter \
    { \
        _JESynthesize_set_##ownership(type, getter); \
    }


#define _JESynthesize_get_assign(type, getter) \
    ({ \
        /* We use an array so the initializer syntax will give us a nice zeroed-out value as default. */ \
        typeof(type) _je_value[1] = {}; \
        [(NSValue *)objc_getAssociatedObject(self, _JESynthesizeKey_##getter) getValue:_je_value]; \
        _je_value[0]; \
    })

#define _JESynthesize_get_unsafe_unretained(type, getter) \
    objc_getAssociatedObject(self, _JESynthesizeKey_##getter);

#define _JESynthesize_get_strong    _JESynthesize_get_unsafe_unretained

#define _JESynthesize_get_retain    _JESynthesize_get_unsafe_unretained

#define _JESynthesize_get_copy      _JESynthesize_get_unsafe_unretained

#define _JESynthesize_get_weak(type, getter) \
    ((_JEAssociatedObjectsWeakWrapper *)objc_getAssociatedObject(self, _JESynthesizeKey_##getter)).weakObject

#define _JESynthesize_set_assign(type, getter) \
    objc_setAssociatedObject(self, \
                             _JESynthesizeKey_##getter, \
                             [[NSValue alloc] initWithBytes:&getter objCType:@encode(type)], \
                             OBJC_ASSOCIATION_RETAIN_NONATOMIC);

#define _JESynthesize_set_unsafe_unretained(type, getter) \
    objc_setAssociatedObject(self, \
                             _JESynthesizeKey_##getter, \
                             getter, \
                             OBJC_ASSOCIATION_ASSIGN);

#define _JESynthesize_set_strong(type, getter) \
    objc_setAssociatedObject(self, \
                             _JESynthesizeKey_##getter, \
                             getter, \
                             OBJC_ASSOCIATION_RETAIN_NONATOMIC);

#define _JESynthesize_set_retain _JESynthesize_set_strong

#define _JESynthesize_set_copy(type, getter) \
    objc_setAssociatedObject(self, \
                             _JESynthesizeKey_##getter, \
                             getter, \
                             OBJC_ASSOCIATION_COPY_NONATOMIC);

#define _JESynthesize_set_weak(type, getter) \
    objc_setAssociatedObject(self, \
                             _JESynthesizeKey_##getter, \
                             [[_JEAssociatedObjectsWeakWrapper alloc] initWithWeakObject:getter], \
                             OBJC_ASSOCIATION_RETAIN_NONATOMIC);
                             
#endif