## 7

### Bugs
- The `userId` conversion using `Int(key) ?? 0` could default to a potentially unintended `0` if the conversion fails, which might mask underlying data issues.

### Optimizations
- Consider adding error handling or logging for `Int(key) ?? 0` conversion to better manage unexpected data.
- The `Category` enum values such as "subs" might benefit from more descriptive naming for clarity.
- Instead of `TimeInterval(check_time)`, use more descriptive conversion explanations or functions to improve code readability.
  
### Good points
- Usage of Swift's `Hashable` and `Sendable` protocols to ensure safety and future-proof the data structures.
- Organized struct with clear separation between data handling and decoding, enhancing maintainability.
- Proper utilization of Swift's raw strings in the enum declaration.
  
### Summary
The code is well-structured and demonstrates good practices by leveraging Swift language features like `Hashable` and `Sendable`, ensuring a well-defined type-safe approach for handling user notifications. However, small improvements like error handling for the `userId` conversion and use of descriptive variable names can enhance robustness and readability.

### Open source alternatives
- [SwiftNotificationCenter](https://github.com/nicklockwood/SwiftNotificationCenter): Provides broadcast-style notifications for Swift.
- [UserNotifications framework by Apple](https://developer.apple.com/documentation/usernotifications): An alternative for handling notifications with official Apple support.