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
