If your iPhone camera screen turns purple during photos or video calls, it's likely a hardware issue. To diagnose and fix the problem, follow these steps:
1. Check for software issues by restarting your iPhone, updating iOS, and resetting all settings.
2. Check camera settings by switching between the front and rear cameras, and checking third-party apps.
3. Inspect hardware for physical damage and remove any cases or covers.
4. Perform a hardware diagnostic by running Apple's diagnostic tool or contacting Apple Support.
5. Restore your iPhone by backing up data and restoring it. If the issue persists, seek professional repair.