Sure, here is the Bitcoin Core Objective-C open source library for iOS.
Supported features include:
- Encoding/decoding addresses: P2PK, P2PKH, P2SH, WIF format (BTCAddress).
- Transaction building blocks: inputs, outputs, scripts (BTCTransaction, BTCScript).
- EC keys and signatures (BTCKey).
- High-level convenient and safe transaction builder (BTCTransactionBuilder).
- Parsing and composing bitcoin URLs and payment requests (BTCBitcoinURL).
- QR Code generator and scanner in a unified API (iOS only for now; BTCQRCode).
- BIP32, BIP44 hierarchical deterministic wallets (BTCKeychain).
- BIP39 implementation (BTCMnemonic).
- BIP70 implementation (BTCPaymentProtocol).
- Automatic Encrypted Wallet Backup scheme (BTCEncryptedBackup).
and more under development (pls see their roadmap section)