I’m enhancing our macOS game so players can buy in-game items with cryptocurrency instead of traditional in-app purchases. The build already runs smoothly in Swift, but I now need a developer who can wire in secure, real-time payments for Bitcoin, Ethereum, Litecoin, and Sol (Solana). Your task is to add a payment layer that: • Invokes the user’s chosen wallet, signs the transaction, and confirms it on chain before unlocking the item. • Handles refunds or failed transactions gracefully. • Stores only the minimum metadata required for compliance while keeping private keys off device. • Plays nicely with Apple’s sandbox/test-flight environment and translates cleanly to production. I’m flexible on timeline—there’s no hard deadline—so quality and security come first. Once the module is stable I’ll test it with our staging server; when both sides sync reliably we can close out the job. If you know macOS frameworks, Swift / Objective-C, and have shipped crypto payment flows before, let’s talk about the implementation path and any SDKs you prefer (Web3, Solana Mobile Stack, etc.).