iOS利用摄像头获取环境光感参数的方法

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：

#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：

1. 首先引入avfoundation框架和imageio/imageio.h声明文件
2. 遵循avcapturevideodataoutputsamplebufferdelegate协议
3. 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
4. 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。