YardWallet is a decentralized bitcoin wallet based on HD Wallet (BIP32) technology. It gives you 100% control of your bitcoins.
What do you mean by a decentralized bitcoin wallet? It seems to be a wallet app for mobile devices. Do you mean it is a wallet that does not rely on external servers?
Yes it's a wallet app for iPhone. The addresses of the wallet rely on the seed value on your phone and you can control your bitcoins completely.
Only some features just like sending bitcoins with email accounts need the external servers.
If you are interested in the app, please download it and have a try. Thanks.