Linking to macOS frameworks

Maurizio Cimadamore maurizio.cimadamore at
Wed May 19 21:12:24 UTC 2021

I see.

Obviously some kind of workaround is happening behind the scene when 
dlopen is invoked with that library name, as a compatibility measure.

If you load this:


Do you, by any change, get access to the symbols you want?

Anyway - to your original question, LibraryLookup.ofPath works with a 
library file in the file system. Here it seems a case where libraries 
are not in the file system, but in some other cache, and dlopen has been 
instructed to "work" when asked with certain well-known names.

In this case, if the above trick (libSystem) doesn't work, the only 
thing left to you might well be calling dlopen directly.


On 19/05/2021 20:31, Clayton Walker wrote:
> Hi Maurizio,
> Yes, UserNotification is a library, but unfortunately
> UserNotification.dylib is no longer in that folder.
> Per this page;!!GqivPVa7Brio!PxJkXokERrp3NAcaRqK7q1eIHPqhs9AWyxmbu4_AfBKvGVbf2OcqtR2HUvwImxChbwHDpmE$ ,
> Apple's release notes state
> `copies of dynamic libraries are no longer present on the filesystem`.
> So while previously they did exist on the filesystem, now they're not.
> dlopen still handles the path on macOS Big Sur,
> dlopen("/System/Library/Frameworks/UserNotifications.framework/Versions/Current/UserNotifications");
> works.
> On Wed, May 19, 2021 at 11:03 AM Maurizio Cimadamore
> <maurizio.cimadamore at> wrote:
>> Hi Clayton,
>> Is UserNotification a library? E.g. is there a file
>> UserNotification.dylib in that folder?
>> If so, just use "Library.ofPath" and include the suffix - as that method
>> wants the library absolute path.
>> Maurizio
>> On 19/05/2021 17:46, Clayton Walker wrote:
>>> Hello,
>>> I'm working on a project that would let you call objective-c functions from
>>> java, without first needing to wrap the api in a shared library. While this
>>> works for symbols that are already available
>>> (i.e.LibraryLookup.ofDefault().lookup("objc_getClass")), it doesn't work
>>> for symbols that are in another framework.
>>> For example, I would like to be able to write something like this:
>>> LibraryLookup.ofLibrary("/System/Library/Frameworks/UserNotifications.framework/Versions/Current/UserNotifications");
>>> // or
>>> LibraryLookup.ofPath(Path.of("/System/Library/Frameworks/UserNotifications.framework/Versions/Current/UserNotifications"));
>>> however this currently doesn't work. The first call throws with "Directory
>>> separator should not appear in library name", second one throws with
>>> "Library not found".
>>> I've been able to work around this by using dlopen
>>> MemoryAddress l1;
>>> try (var c =
>>> CLinker.toCString("/System/Library/Frameworks/UserNotifications.framework/Versions/Current/UserNotifications"))
>>> {
>>>       l1 = (MemoryAddress) dlopen.invokeExact(c.address(), 1);
>>> }
>>> but this seems rather strange. It looks like LibraryLookup.ofPath requires
>>> the path to exist, whereas in Big Sur the files no longer exist (via
>>>;!!GqivPVa7Brio!PxJkXokERrp3NAcaRqK7q1eIHPqhs9AWyxmbu4_AfBKvGVbf2OcqtR2HUvwImxChS2opDZY$ ).

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