I would wish to know more about how to erase 100% data of a used iPhone.
Basically, technician from Apple Store only said “Erase & Clear” within the iPhone setting could do all the work perfectly and all data of an iPhone are encrypted, so there is no way anyone could steal any traces of the data.
I am not sure about that answer as I believe the hard drive in a iPhone works the same as computers which means old data could only be completely erased unless they have been overwritten by new data. My speculation was confirmed by a iPhone data eraser tool called “iShredder”, as it claimed it would help to erase everything up to security agency standard.
So my question is if “iShredder” is a legitimate tool for going forward about erasing iPhone’s data in the most professional way? What do you think?
If the iPhone had used some APPs in connection with entertainment like music and movies, sometimes they offer you an off-line viewing by caching the content, does that mean it is not different from downloading those data on your hard drive of the iPhone, which means you would have to overwrite them completely in order to erase them, and “Clearing cache” option in those Apps only marked them as deleted but not exactly erasing them?
Also, when you are trying to delete photos when the iCloud is full, it says they would be deleted immediately and you would not be able to recover them from “Recently Deleted”, does that those photos were also completely gone or again were just marked as “Free Space” until new data overwrites them in the hard drive?
Sorry for a series of questions and looking forward to your advices on this! Many thanks!