I’m building a native iOS “EMI locker” that can temporarily restrict phone usage whenever a scheduled instalment is missed, then lift the restriction the moment the payment is confirmed. The core workflow is straightforward: the user registers a repayment schedule, the app monitors due dates, sends an email reminder ahead of each one, and—if no payment confirmation is received—activates a lock screen that limits access to non-essential apps until the account is up-to-date. Key behaviour I need implemented: • Lock phone on missed payments – preferably by leveraging Apple MDM / DeviceManagement or the Guided Access API so the solution stays within Apple’s security guidelines (no jailbreak work-arounds). • Email payment reminders – configurable lead time (e.g., 1 day, 3 days). • Usage reports – daily and monthly CSV or PDF summarising lock events, total restricted hours, and reminder history. Acceptance criteria 1. Compatible with the latest two major iOS versions on iPhone. 2. Lock screen cannot be bypassed without payment flag or admin override. 3. Reminder emails are sent via SMTP or a service like SendGrid, with logs stored locally. 4. Reports are generated on-device and exportable through the standard share sheet. 5. Clean, well-documented Swift code (SwiftUI preferred but UIKit acceptable) plus short README for build/run instructions. Once the core is stable I have scope for further analytics features, so a modular design will be appreciated.