ios摄像功能（相机ios感光度）

本文介绍了iOS利用摄像头获取环境光感参数的方法，分享给大家，具体如下：

不多说，代码如下：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 #import "LightSensitiveViewController.h" @import AVFoundation; #import <ImageIO/ImageIO.h> @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 = @"光感"; [self lightSensitive]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } #pragma mark- 光感 - (void)lightSensitive { // 1.获取硬件设备 AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; // 2.创建输入流 AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc]initWithDevice:device error:nil]; // 3.创建设备输出流 AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init]; [output setSampleBufferDelegate:self queue:dispatch_get_main_queue()]; // AVCaptureSession属性 self.session = [[AVCaptureSession alloc]init]; // 设置为高质量采集率 [self.session setSessionPreset:AVCaptureSessionPresetHigh]; // 添加会话输入和输出 if ([self.session canAddInput:input]) { [self.session addInput:input]; } if ([self.session canAddOutput:output]) { [self.session addOutput:output]; } // 9.启动会话 [self.session startRunning]; } #pragma mark- AVCaptureVideoDataOutputSampleBufferDelegate的方法 - (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); // 根据brightnessValue的值来打开和关闭闪光灯 AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; BOOL result = [device hasTorch];// 判断设备是否有闪光灯 if ((brightnessValue < 0) && result) {// 打开闪光灯 [device lockForConfiguration:nil]; [device setTorchMode: AVCaptureTorchModeOn];//开 [device unlockForConfiguration]; }else if((brightnessValue > 0) && result) {// 关闭闪光灯 [device lockForConfiguration:nil]; [device setTorchMode: AVCaptureTorchModeOff];//关 [device unlockForConfiguration]; } } @end

注意点：

首先引入AVFoundation框架和ImageIO/ImageIO.h声明文件
遵循AVCaptureVideoDataOutputSampleBufferDelegate协议
AVCaptureSession对象要定义为属性，确保有对象在一直引用AVCaptureSession对象；否则如果在lightSensitive方法中定义并初始化AVCaptureSession对象，会造成AVCaptureSession对象提前释放， [self.session startRunning];会失效
实现AVCaptureVideoDataOutputSampleBufferDelegate的代理方法，参数brightnessValue就是周围环境的亮度参数了，范围大概在-5~~12之间,参数数值越大，环境越亮

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。

原文链接：http://www.jianshu.com/p/f308d0aeced0