Meditation Tone Generator 4+

Modernized User Interface:
Transitioned from a basic UIKit setup to a SwiftUI-based interface with a visually appealing design, including a gradient background, glass card effects, and custom controls (e.g., Knob, GlossyButtonStyle), improving user experience and aligning with App Store expectations for polished apps.
Expanded Audio Functionality:
Added support for multiple waveforms (Sine, Square, Triangle, Sawtooth), binaural beats, modulation, phase shift, and delay effects, offering a richer feature set that enhances app value and appeal to users.
Implemented real-time audio synthesis with AVAudioSourceNode, ensuring high-quality sound output suitable for a professional release.
Monetization Integration:
Added StoreKit for a $3.99/month subscription to unlock premium features (e.g., frequency prescriptions) and remove ads, complying with App Store in-app purchase guidelines.
Integrated Google Mobile Ads (GADRewardedInterstitialAd) for non-subscribers, providing a freemium model that adheres to App Store advertising policies.
Subscription Management:
Included subscription status checking (checkSubscriptionStatus) and restoration via SKPaymentQueue, ensuring compliance with App Store requirements for handling purchases and renewals transparently.
Enhanced User Engagement:
Added a waveform visualization (WaveformVisualization) that animates during playback, making the app more interactive and visually engaging.
Introduced frequency presets (e.g., Healing: 528 Hz) and a prescription system for subscribers, offering unique content that justifies the app’s presence on the App Store.
Export and Sharing Capabilities:
Implemented tone export functionality (exportTone) as .m4a files, integrated with a ShareSheet, allowing users to share prescriptions—enhancing social features and user retention, which are attractive for App Store approval.
Settings and Customization:
Added an AppSettings class and a SettingsView for options like background play and subscription management, improving user control and meeting App Store usability standards.
Audio Session Improvements:
Retained and refined AudioSessionManager with updated updateNowPlayingInfo (using a system image) and enhanced interruption handling with custom notifications, ensuring robust background playback and lock screen controls compliant with App Store audio app expectations.
App Store Compliance Features:
Integrated TestFlight initialization (initializeApp) and StoreKit review prompts (SKStoreReviewController), aligning with App Store guidelines for beta testing and user feedback.
Added privacy-focused design (e.g., no explicit data collection in the code), preparing for App Store privacy label requirements.
Polish and Professionalism:
Included haptic feedback (UIImpactFeedbackGenerator) for button presses, enhancing tactile interaction and perceived quality.
Added a progress view for export operations (isExporting), improving user feedback during long-running tasks, a detail that reflects App Store-ready refinement.