I have just gone through the cloud kit doc as in this link cloudkit but not getting clear about to modify database records for public database. As per this description in cloudkit framework.
Using Public Database, as specified in image by default data are world readable, owner writable. That means only owner can modify his data other user can only read? Suppose, using public database, user A can access records of user B, But can user A modify records of user B in same application.
Please suggest. Thanks.
In the CloudKit dashboard you are able to change the access rights. So it would be possible to make records writable by others. You do have to be careful with this. When your app runs on a jailbroken device, then it's possible to execute methods with arbitrary arguments. This is a high security risk.
if you set your security setting within the record types on the dashboard, you can have all your public records set to be writeable by anyone without messing with the security roles.
Set Authenticated to Write
Set Creator to create.
p.s. you cannot 'world' read from the simulator, you need to be logged in on that. On the device though, you don't need to be logged in to read the public database :-) which is nice.
来源：https://stackoverflow.com/questions/25600556/cloudkit-can-we-modify-data-of-public-database