iOS Payment Integration Modernization

We are seeking an experienced iOS developer to modernize payment and seller-payout functionality in an existing Swift marketplace app. The app uses UIKit, Storyboards, CocoaPods, and legacy Stripe and Plaid integrations. Scope Audit and upgrade Stripe, Apple Pay, Plaid, and Stripe Connect. Modernize card payments, saved payment methods, bank linking, refunds, and payouts. Replace deprecated SDK methods. Move sensitive payment logic and secret credentials to secure backend endpoints. Improve error handling, retries, environment configuration, and duplicate-charge prevention. Migrate dependencies to Swift Package Manager where practical. Test critical success, failure, cancellation, and interruption scenarios. Deliver a TestFlight-ready build. Required Experience Advanced Swift and UIKit Stripe PaymentSheet, PaymentIntents, Apple Pay, and Connect Plaid Link for iOS Secure client-server payment architecture Marketplace payments, refunds, bank verification, and payouts TestFlight and App Store releases Please Include Relevant Stripe and Plaid experience Examples of similar marketplace work Availability, timeline, and rate