objc_setAssociatedObject unavailable in iPhone simulator - iphone

Question

In the 3.1 SDk, Apple added support for associated objects.
However, the simulator will not compile code that includes references to objc_setAssociatedObject, objc_getAssociatedObject, et al. (Undeclared errors)
Is there away around this? Can I make the iPhone simulator compile this code? I would hate to have to do all testing on the device.
Update
Bug Filed:
rdar://7477326

Answer 1

I don't think this will be fixed in the 3.x SDKs, so another fix is to just define the functions and call through to the next definition via a dynamic lookup.
Header:
#if TARGET_IPHONE_SIMULATOR
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;
void objc_setAssociatedObject(id object, void *key, id value, objc_AssociationPolicy policy);
id objc_getAssociatedObject(id object, void *key);
void objc_removeAssociatedObjects(id object);
#endif
Implementation:
#if TARGET_IPHONE_SIMULATOR
void objc_setAssociatedObject(id object, void *key, id value, objc_AssociationPolicy policy) {
((void (*)(id, void *, id, objc_AssociationPolicy))
dlsym(RTLD_NEXT, "objc_setAssociatedObject")) (object, key, value, policy);
}
id objc_getAssociatedObject(id object, void *key) {
return ((id (*)(id, void *))
dlsym(RTLD_NEXT, "objc_getAssociatedObject"))(object, key);
}
void objc_removeAssociatedObjects(id object) {
((void (*)(id))
dlsym(RTLD_NEXT, "objc_removeAssociatedObjects"))(object);
}
#endif

Answer 2

A quick and dirty workaround (largely untested, may be buggy):
#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