PHAdjustmentData limit

fromHi,


We can add PHAdjustmentData to our PHAsset while updating so that we can restore the edits.


I have two questions regarding it.


What is the limit on size of data that can be added to in the "data" property of PHAdjustmentData ?


I have seen application which are using PHAdjustmentData to store the informations but when I tried to read the PHAdjustmentData from photos edited by such apps, I can not see that formatIdentifier, formatVersion and data is shown as a class. How is it possible to set PHAdjustmentData something which can not be read by other apps ?



Thanks