objc_setAssociatedObject在iPhone模拟器中不可用

Question

在3.1 SDk中,Apple增加了对相关对象的支持.

但是,模拟器不会编译包含对objc_setAssociatedObject,objc_getAssociatedObject等的引用的代码.(未声明的错误)

有没有解决的办法？我可以让iPhone模拟器编译这段代码吗？我不想在设备上进行所有测试.

---

更新

Bug Filed:rdar:// 7477326

Answer 1

一个快速而肮脏的解决方法（基本上未经测试，可能有错误）：

#if TARGET_IPHONE_SIMULATOR

#import <objc/runtime.h>

enum {
    OBJC_ASSOCIATION_ASSIGN = 0,
    OBJC_ASSOCIATION_RETAIN_NONATOMIC = 1,
    OBJC_ASSOCIATION_COPY_NONATOMIC = 3,
    OBJC_ASSOCIATION_RETAIN = 01401,
    OBJC_ASSOCIATION_COPY = 01403
};
typedef uintptr_t objc_AssociationPolicy;

@implementation NSObject (OTAssociatedObjectsSimulator)

static CFMutableDictionaryRef theDictionaries = nil;

static void Swizzle(Class c, SEL orig, SEL new) // swizzling by Mike Ash
{
    Method origMethod = class_getInstanceMethod(c, orig);
    Method newMethod = class_getInstanceMethod(c, new);
    if (class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
        class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    else
        method_exchangeImplementations(origMethod, newMethod);
}

- (NSMutableDictionary *)otAssociatedObjectsDictionary
{
    if (!theDictionaries)
    {
        theDictionaries = CFDictionaryCreateMutable(NULL, 0, NULL, &kCFTypeDictionaryValueCallBacks);
        Swizzle([NSObject class], @selector(dealloc), @selector(otAssociatedObjectSimulatorDealloc));
    }

    NSMutableDictionary *dictionary = (id)CFDictionaryGetValue(theDictionaries, self);
    if (!dictionary)
    {
        dictionary = [NSMutableDictionary dictionary];
        CFDictionaryAddValue(theDictionaries, self, dictionary);
    }

    return dictionary;
}

- (void)otAssociatedObjectSimulatorDealloc
{
    CFDictionaryRemoveValue(theDictionaries, self);
    [self otAssociatedObjectSimulatorDealloc];
}

@end

void objc_setAssociatedObject(id object, void *key, id value, objc_AssociationPolicy policy)
{
    NSCAssert(policy == OBJC_ASSOCIATION_RETAIN_NONATOMIC, @"Only OBJC_ASSOCIATION_RETAIN_NONATOMIC supported");

    [[object otAssociatedObjectsDictionary] setObject:value forKey:[NSValue valueWithPointer:key]];
}

id objc_getAssociatedObject(id object, void *key)
{
    return [[object otAssociatedObjectsDictionary] objectForKey:[NSValue valueWithPointer:key]];
}

void objc_removeAssociatedObjects(id object)
{
    [[object otAssociatedObjectsDictionary] removeAllObjects];
}

#endif