Alexis wrote:
Apple gives the developers a great development toolkit, a perfectly well organized worldwide shop for their apps
The toolkit is not really great and I have no intention to market my programs. On every computer I have owned so far (quite a few) I was able to write programs for my own use. Free of charge, unless the development software would cost something (which on a unix based computer is not usually the case). The iPad is the first one which doesn’t let me write my programs without an annual (!) payment.
I am not a software engineer myself, but I think that you CAN install your own apps on your iPad simply with only your Apple-ID:
http://blog.ionic.io/deploying-to-a-device-without-an-apple-developer-account/
I do not know if this is correct.
As others have said, to be able to install apps on an iOS device you need to be a Registered Developer with Apple. It costs €99 per year.
Once installed, your app can not see any the files belonging to other apps.
Sharing of files on iOS is done differently. You present the file to the OS, and it offers the user apps that can open that file type. The programmer has no access to other programs files; it can’t even see if they exist. This makes it very hard to spread viruses etc.
It would be a lot easier to
I realise point #3 potentially limits the utility, but the payoff is worth it, and if you have a girlfriend, it comes down just to the email filtering bit 
Alexis wrote:
I am not a software engineer myself, but I think that you CAN install your own apps on your iPad simply with only your Apple-ID:http://blog.ionic.io/deploying-to-a-device-without-an-apple-developer-account/
I do not know if this is correct.
I had a quick look but did not try it out (would have to install iOS 9 on by iPad after which I can probably throw away 50% of my older apps). This method obviously uses some obscure hole/bug in the iTunes Store by which you can circumvent the annual payment using not your own (!) but some new Apple ID (I wouldn’t even know how to create a new Apple ID for me). I am pretty sure that this hole has been plugged by now, and even if not, the procedure is complicated and there is always the risk that your selfmade Apps will be disabled the day Apple finds out about them.
will be disabled the day Apple finds out about them.
That is yet another reason for rooting a device – IOS or android. You can put stuff in the hosts file to block apps talking to Apple, Google or anybody else. You can stop selected apps from seeing the internet. So critical stuff doesn’t just suddenly stop working.
One does the same on PCs running critical stuff. Block apps in the firewall, or via lmhosts.
Peter wrote:
That is yet another reason for rooting a device – IOS or android.
I was under the impression that:
1. IOS 9 and 10 appear to be supported.
2. There are other ways to solve that one
