How to share keychain data between iOS applications

I am describing a problem for which it took me quite some time to learn the answer.

The "GenericKeychain" example is a good start at providing a wrapper for sharing keychain data between applications when using the accessGroup in the init.

However, implementing this in my app yielded an obscure e开发者_运维知识库rror code (which took forever to locate) -25243, which means: No access control.

I ran Apple's example app (GenericKeychain) on my iPad only to get the same error. Huh?

Does Apple's documentation fail to deliver on what is necessary to accomplish this?

After some (a lot of) digging throughout the web, I found the answer. The access Group that you use when constructing your KeychainItemWrapper class must ALSO be specified in each of your application's Entitlements.plist file in the "keychain-access-groups" section.

It seems almost obvious now that I see "keychain-access-groups". However, I had no idea to even look there. Hope this helps others.

Actually it's not hard to do. Please follow the steps.

App1:

1. Open your App's target Capabilities and enable KeyChain Sharing.
2. Add a identifier. (eg : com.example.sharedaccess)
3. Add "UICKeyChainStore" to your project.
4. Be sure you have a team id added to your App1 project.
5. Add Security.framework to your App1 project.

6. And add these codes to somewhere you need.

   [UICKeyChainStore setString:@"someValue" forKey:@"someKey" service:@"someService"];
   

App2:

• Open your App's target Capabilities and enable KeyChain Sharing.
• Add a identifier. (eg : com.example.sharedaccess)
• Add "UICKeyChainStore" to your project.
• Be sure you have a team id added to your App2 project.
• Add Security.framework to your App2 project.

• And add these codes to somewhere you need.

  NSString *string = [UICKeyChainStore stringForKey:@"someKey" service:@"someService"];
  

• Your TeamIDs should be same for both projects.

• I tried these steps on a real iPhone device.
• I also tried these steps with Automatic and iOs Development provisioning profile.
• My apps' bundle identifiers were like that : com.example.app1, com.example.app2.