Avoid freezing issues by removing session operations during the app lifecycle.

[nullLuli]

I used FastttCamera in my app and collected some freezing stack traces by Apple’s MetricKit:

0   libsystem_kernel.dylib        	0x00000001b72ad4e0 mach_msg_trap + 8
1   libsystem_kernel.dylib        	0x00000001b72adb24 mach_msg + 76 (mach_msg.c:119)
2   CoreFoundation                	0x0000000180408820 __CFRunLoopServiceMachPort + 372 (CFRunLoop.c:2646)
3   CoreFoundation                	0x000000018040ccac __CFRunLoopRun + 1180 (CFRunLoop.c:3000)
4   CoreFoundation                	0x00000001804206b8 CFRunLoopRunSpecific + 600 (CFRunLoop.c:3268)
5   AVFCore                       	0x0000000189a5d60c -[AVRunLoopCondition _waitInMode:untilDate:] + 412 (AVRunLoopCondition.m:174)
6   AVFCapture                    	0x000000019f46125c -[AVCaptureSession _stopFigCaptureSession] + 436 (AVCaptureSession.m:2031)
7   AVFCapture                    	0x000000019f444284 -[AVCaptureSession _setRunning:] + 180 (AVCaptureSession.m:2103)

After reviewing Apple's documentation, I noticed that in the camera demo provided by Apple, the session operations (such as session init, start running, stop running) are not triggered during app lifecycle changes, and everything functions normally. So I removed this part of the code from my app, and the freezing issues disappeared. Therefore, I believe that frequent session operations can overburden the camera, leading to freezing problems.