Explained: App Syncing

Meet Installd.

He lives in all iPhones and iPod Touches, and his address is /usr/libexec/installd. He is in charge of installation and compression of apps.

This is his job:

And this too:

Yes, let’s forget about the horrid drawings for a moment. You notice the blue boxes in both pictures? The processes fail. That’s what happens when you try to install/sync cracked apps using the original Installd.


How do you fix that? By “patching” Installd.

  • AppSync is a system tweak. When you install AppSync from Cydia (after adding the source cydia.hackulo.us), AppSync renames Installd to Installd.backup, and invites a tenant to live in place of the original Installd. This new Installd works just like the original except that it totally skips the blue boxes, so the processes don’t fail anymore.
  • Installd Patch is another system tweak (source iphone.org.hk/apt). Instead of forcing Installd out of his home, the patch changes Installd’s life. Hence the name “patch”, because it patches Installd to make it forget to run the blue boxes.

By installing either of them, you are patching Installd. Both tweaks do not affect your legitimately purchased apps (*). If it’s not immediately intuitive to you, get an image editor and erase the entire blue box from each of the pictures. What you get then is the process flow chart after AppSync (or Installd Patch) is applied. No more DRM checks. No more failing, no more deleting. Who cares if the application has DRM protection or not? The application gets installed/synced regardless of that.

(*) A free app is also considered a purchase because it is reflected on your iTunes bill as a purchase.

Both AppSync and Installd Patch get the same job done, and DON’T EVER have both of them installed at the same time on your iDevice. Installd will get mad and go on strike.


And this is why you need AppSync if you want to do any of the following:

  • Use Install0us 2.5 to install cracked apps
  • Sync cracked apps from computer to iDevice
  • Sync cracked apps from iDevice to computer



But why is Installous 2.0.4 able to install cracked apps without a patched Installd? Because Installous installs like this:

Many dependencies are required for Installous 2’s installation method (from uncon) because it doesn’t use the native Installd (hence Installd doesn’t need to be patched for Installous 2 to work). It also means you’re not restricted by the Installd framework, for example, patched Installd files will give an “This is not a test user account” error when you try to install in-app purchases from a legitimately purchased app.

As a workaround, you can swap the original and patched Installd files around by renaming them using iFile from Cydia. If you used Installd Patch, you will need to find an original Installd to use for swapping.



Regardless if you use Installous 2 or Install0us 2.5, if you’re on OS 3 or above, you have always needed a patched Installd to do any syncing of cracked apps between iDevice and computer, as should be obvious from the diagrams above. Syncing of legitimately purchased apps carries on as per normal with or without a patched Installd.


PS: For a text version, read Explained: Patching The Installd.