Why IOS doesn’t have new versions of ppsspp???

[Abbanon]

The main developers handle the Windows and Android builds primarily. All other builds aren't as big of a priority because the userbases for them are so small by comparison.
That's why the project is open source: So if someone wants to make an up-to-date iOS build, they have both the ability and the rights to do it. But nobody seems to have done it yet.
Not to mention, iOS handles things weird with things known as certificates. It's a type of registry file, to put it simply. An app needs a certificate to be allowed to run on a non-jailbroken iOS device.
If you don't have a certificate in the app, after roughly 7 days the app will refuse to work anymore, more or less.

So it's a combination of [A] Nobody stepping up to the plate to update the iOS builds, [B] The small userbase for iOS PPSSPP, and [C] The ridiculous certificate thing that Apple requires for every app.
And unfortunately, Apple doesn't want to give certificates for PPSSPP (as far as I'm aware).

Some users are looking for a way to keep PPSSPP on their iOS device without having to jailbreak it. If anything is discovered and proven to work, hopefully they will let the rest of us know.
But that's more or less the whole situation.