iOS는 카메라를 이용하여 환경 광감각 파라미터를 얻는다

#import "LightSensitiveViewController.h"

@import AVFoundation;

#import 

@interface LightSensitiveViewController ()< AVCaptureVideoDataOutputSampleBufferDelegate>

@property (nonatomic, strong) AVCaptureSession *session;

@end

@implementation LightSensitiveViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    self.view.backgroundColor = [UIColor whiteColor];
    
    self.navigationItem.title = @"  ";
    [self lightSensitive];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark-   
- (void)lightSensitive {
    
    // 1.      
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    
    // 2.     
    AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc]initWithDevice:device error:nil];
    
    // 3.       
    AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
    [output setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
    

    // AVCaptureSession  
    self.session = [[AVCaptureSession alloc]init];
    //          
    [self.session setSessionPreset:AVCaptureSessionPresetHigh];
    //          
    if ([self.session canAddInput:input]) {
        [self.session addInput:input];
    }
    if ([self.session canAddOutput:output]) {
        [self.session addOutput:output];
    }
    
    // 9.    
    [self.session startRunning];
    
}

#pragma mark- AVCaptureVideoDataOutputSampleBufferDelegate   
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
    
    CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL,sampleBuffer, kCMAttachmentMode_ShouldPropagate);
    NSDictionary *metadata = [[NSMutableDictionary alloc] initWithDictionary:(__bridge NSDictionary*)metadataDict];
    CFRelease(metadataDict);
    NSDictionary *exifMetadata = [[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary] mutableCopy];
    float brightnessValue = [[exifMetadata objectForKey:(NSString *)kCGImagePropertyExifBrightnessValue] floatValue];
    
    NSLog(@"%f",brightnessValue);
    
    
    //   brightnessValue           
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    BOOL result = [device hasTorch];//           
    if ((brightnessValue < 0) && result) {//      
        
        [device lockForConfiguration:nil];
        
        [device setTorchMode: AVCaptureTorchModeOn];// 
        
        [device unlockForConfiguration];
        
    }else if((brightnessValue > 0) && result) {//      
        
        [device lockForConfiguration:nil];
        [device setTorchMode: AVCaptureTorchModeOff];// 
        [device unlockForConfiguration];
        
    }
    
}

@end