You are always free to create your own wallet (and preferably share it with the community)
The problem is that a very small minority of techy people does use an iphone / iOs.
Most techies/developers prefer full control over their device, open source and a fair price. Apple's products are exactly the opposite.
And that's mostly the reason why you see a big range of awesome applications (wallets, bitcoin-related and not-bitcoin-related) for android, but almost none for iOs.
Actually, i am not sure whether i have met any IT-guy with apple products at all yet.
I will work on an iOS wallet, will make an electrum like version - Light, supporting segwit / multisig and LN.
Devs do not use Apple products (or microsoft or whatever) and tend to use Open source, I have never used any OS than Linux so I can relate, but these devs have family members and relatives using iPhones.