Add Swift print redirection to System Log

[loinsir]

Summary

Add Swift print() and debugPrint() output capture to FLEX System Log viewer. Swift print statements now appear in System Log with [SwiftPrint]
prefix alongside NSLog and os_log messages.

Changes

Core Implementation

• FLEXSwiftPrintRedirector: New Objective-C class that redirects stdout/stderr to capture Swift print output
  • Uses NSPipe to intercept stdout/stderr file descriptors
  • Implements line buffering to handle partial pipe reads correctly
  • Callback-based architecture for direct FLEX integration without going through NSLog/os_log
  • Preserves original console output while capturing for FLEX

Integration

• System Log view automatically enables Swift print redirection on load
• Captured messages are directly delivered to FLEX via message handler callback
• All Swift print output appears with [SwiftPrint] prefix for easy identification

Example App

• Added Swift print test statements in example app timer for demonstration

Technical Details

Why not use NSLog?

• Initially attempted to redirect Swift print to NSLog/os_log, but this caused <compose failure [corrupt log]> errors in the os_log system
• Direct message delivery via callbacks bypasses os_log entirely, avoiding corruption issues

Line Buffering

• NSPipe may deliver partial data chunks that split lines
• Implemented buffering to accumulate partial lines until newline is found
• Ensures complete log messages are displayed without truncation

Test Plan

1. Run FLEXample app
2. Open FLEX System Log viewer
3. Observe Swift print statements appearing with [SwiftPrint] prefix
4. Verify console output still works normally