前文：
今天来详细写一下扫一扫实现，基本上实现扫一扫有三个库，分别是ZBar,ZXing,AVFoundation，在IOS7以前是没有AVFoundation的。
1.ZBar在扫描灵敏度和内存上比ZXing较好，缺点却很多，比如有圆角的二维码很难扫。目前已经停止更新
2.ZXing是GoogleCode上的一个开源的条形码扫码库，是用java设计的，连Google Glass都在使用。但有人为了追求更高效率以及可移植性，出现了c++ port. Github上的Objectivc-C port，其实就是用OC代码封装了一下而已，而且已经停止维护。
3.AVFoundation提供原生api扫描二维码，无论在扫描灵敏度和性能上来说都是最优的，所以毫无疑问我们应该切换到AVFoundation，但是只兼容IOS7及以上，如果是IOS7之前的版本就要使用ZBar或ZXing代替。
我写的比较全面，二维码，条形码，扫描区域设置，光感传感器应用，闪光灯显示与隐藏，闪光灯打开与关闭，相册获取二维码扫描
头文件：AVFoundation 是扫描需要用到的库
ImageIO 是闪光灯需要用到的库
#import <AVFoundation/AVFoundation.h>
#import <ImageIO/ImageIO.h>
代理协议：
AVCaptureMetadataOutputObjectsDelegate 扫描二维码结果代理
AVCaptureVideoDataOutputSampleBufferDelegate 周围环境光感传感器代理
UINavigationControllerDelegate、UIImagePickerControllerDelegate 选择相册图片代理
<AVCaptureMetadataOutputObjectsDelegate,AVCaptureVideoDataOutputSampleBufferDelegate,UINavigationControllerDelegate,UIImagePickerControllerDelegate>
属性：
//显示图层
@property(nonatomic,strong)AVCaptureVideoPreviewLayer *layer;
//捕捉会话
@property(nonatomic,strong)AVCaptureSession *session;
//辅助区域框
@property(nonatomic,strong)UIView * cyanView;
//打开灯光btn,默认为hidden
@property(nonatomic,strong)UIButton * lightBtn;
//获取相册图片进行扫描
@property(nonatomic,strong)UIButton * photoBtn;
//建议先判断一下，是否开启相机权限
//创建状态对象
AVAuthorizationStatus authStatus =[AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
//判断摄像头状态是否可用
if(authStatus==AVAuthorizationStatusAuthorized){
//开始扫描二维码
[self startScan];
}else{
NSLog(@"未开启相机权限，请前往设置中开启");
}
//开始扫描二维码
-(void)startScan{
//1.创建捕捉会话,AVCaptureSession是第一个要被创建的对象，所有的操作都要基于这一个session
self.session = [[AVCaptureSession alloc]init];
//2.添加输入源(数据从摄像头输入)
/*输入源对应的类是AVCaptureInput，该类是一个抽象类，不能被直接实例化
在实际使用中，都是使用他的子类，比如
AVCaptureDeviceInput，
AVCaptureScreenInput(只能用于Mac)，
AVCaptureMetadataInput，
一般情况下，我们是使用AVCaptureDeviceInput，比如从设备的摄像头或者麦克风输入。
AVCaptureDeviceInput的实例化方法如下
*/
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];
[self.session addInput:input];
//3.添加输出数据(示例对象-->类对象-->元类对象-->根元类对象)
/*输入的类是AVCaptureInput，那么输出的类相应的就应该是AVCaptureOutput。
输出不需要和设备挂钩,因为一般情况下，我们的输出要么是音频或视频文件，要么是一些其他的数据，像二维码扫描一般是字符串类型。
所以创建AVCaptureOutput实例就不需要AVCaptureDevice对象。
AVCaptureOutput也同样是一个抽象类，同样要使用其子类，在这里我们扫描二维码，
使用的是AVCaptureMetadataOutput，设置代码如下所示*/
AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
//设置能扫描的区域，这里注意，CGRectMake的x,y和width,height的值是互换位置
output.rectOfInterest=CGRectMake(150/self.view.frame.size.height, 100/self.view.frame.size.width, (self.view.frame.size.width-200)/self.view.frame.size.width, (self.view.frame.size.width-200)/self.view.frame.size.width);
[self.session addOutput:output];
//设置输入元数据的类型(类型是二维码,条形码数据,注意，这个一定要写在添加到session后面，不然要崩溃，如果只需要扫描二维码只需要AVMetadataObjectTypeQRCode，如果还需要扫描条形码，那么全部添加上)
[output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode,
AVMetadataObjectTypeEAN8Code,
AVMetadataObjectTypeEAN13Code,
AVMetadataObjectTypeCode39Code,
AVMetadataObjectTypeCode39Mod43Code,
AVMetadataObjectTypeCode93Code,
AVMetadataObjectTypeCode128Code,
AVMetadataObjectTypePDF417Code,
AVMetadataObjectTypeAztecCode,
AVMetadataObjectTypeUPCECode,
AVMetadataObjectTypeInterleaved2of5Code,
AVMetadataObjectTypeITF14Code,
AVMetadataObjectTypeDataMatrixCode,
]];
//4.添加扫描图层
self.layer = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
self.layer.videoGravity=AVLayerVideoGravityResizeAspectFill;
self.layer.frame = self.view.bounds;
[self.view.layer addSublayer:self.layer];
//5.创建view,通过layer层进行设置边框宽度和颜色,用来辅助展示扫描的区域
UIView * cyanView=[[UIView alloc] initWithFrame:CGRectMake(100, 150, self.view.frame.size.width-200, self.view.frame.size.width-200)];
cyanView.layer.borderWidth=2;
cyanView.layer.borderColor =[UIColor cyanColor].CGColor;
[self.view addSubview:cyanView];
//6.创建检测光感源
AVCaptureVideoDataOutput *guangOutPut = [[AVCaptureVideoDataOutput alloc] init];
[guangOutPut setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
//设置为高质量采集率
[self.session setSessionPreset:AVCaptureSessionPresetHigh];
//把光感源添加到会话
[self.session addOutput:guangOutPut];
//7.闪光灯开关btn
self.lightBtn=[[UIButton alloc]initWithFrame:CGRectMake(150, cyanView.frame.origin.y+cyanView.frame.size.height+100, self.view.frame.size.width-300, self.view.frame.size.width-300)];
self.lightBtn.backgroundColor=[UIColor grayColor];
[self.lightBtn addTarget:self action:@selector(lightBtnClick:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.lightBtn];
//8.获取相册图片进行扫描btn
self.photoBtn=[[UIButton alloc]initWithFrame:CGRectMake(100, self.lightBtn.frame.origin.y+self.lightBtn.frame.size.height+50, self.view.frame.size.width-200, 50)];
[self.photoBtn setTitle:@"相册" forState:UIControlStateNormal];
[self.photoBtn setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
self.photoBtn.backgroundColor=[UIColor orangeColor];
[self.photoBtn addTarget:self action:@selector(photoBtnClick:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:self.photoBtn];
//9.开始扫描
[self.session startRunning];
}
//实现扫描的回调代理方法
- (void)captureOutput:(AVCaptureOutput*)captureOutput didOutputMetadataObjects:(NSArray*)metadataObjects fromConnection:(AVCaptureConnection*)connection{
//如果数组metadataObjects中有数据，metadataObjects是个数组类型
if(metadataObjects.count>0) {
// 获取最终的读取结果，获取数组中最后一个元素，数组中是AVMetadataMachineReadableCodeObject类型对象
AVMetadataMachineReadableCodeObject*object = [metadataObjects lastObject];
NSLog(@"%@",object.stringValue);
//停止扫描
[self.session stopRunning];
//移除扫描层layer
[self.layer removeFromSuperlayer];
}else{
NSLog(@"没有扫描到数据");
}
}
//光感传感器代理
-(void)captureOutput:(AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection*)connection{
//获取光线的值
CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL,sampleBuffer, kCMAttachmentMode_ShouldPropagate);
NSDictionary *metadata = [[NSMutableDictionary alloc] initWithDictionary:(__bridge NSDictionary*)metadataDict];
CFRelease(metadataDict);
NSDictionary *exifMetadata = [[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary] mutableCopy];
floatbrightnessValue = [[exifMetadata objectForKey:(NSString*)kCGImagePropertyExifBrightnessValue]floatValue];
NSLog(@"%f",brightnessValue);
// 根据brightnessValue的值来打开和关闭闪光灯，一般值小于0就需要打开，大于0就关闭
if((brightnessValue <0)) {//显示闪光灯
self.lightBtn.hidden=NO;
}elseif((brightnessValue >0)) {//隐藏闪光灯
self.lightBtn.hidden=YES;
}
}
//闪光灯按钮点击方法
-(void)lightBtnClick:(UIButton*)sender{
//判断当前设备是否有闪光灯
AVCaptureDevice * device=[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
BOOL result=[device hasTorch];
if(result==YES){
if(self.lightBtn.isSelected==NO){
self.lightBtn.selected=YES;
self.lightBtn.backgroundColor=[UIColor greenColor];
[device lockForConfiguration:nil];
[device setTorchMode: AVCaptureTorchModeOn];//开
[device unlockForConfiguration];
}else if(self.lightBtn.isSelected==YES){
self.lightBtn.selected=NO;
self.lightBtn.backgroundColor=[UIColor grayColor];;
[device lockForConfiguration:nil];
[device setTorchMode: AVCaptureTorchModeOff];//关
[device unlockForConfiguration];
}
}else{
NSLog(@"当前设备闪光灯不可用");
}
}
//获取相册图片btn点击方法
-(void)photoBtnClick:(UIButton*)sender{
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
// imagePicker.allowsEditing = YES;
imagePicker.delegate=self;
[self.navigationController presentViewController:imagePicker animated:YES completion:nil];
}
//UIImagePickerControllerDelegate选择图片的回调
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<UIImagePickerControllerInfoKey,id> *)info {
//把UIimage类型转换成CIimage类型
UIImage *pickedImage = info[UIImagePickerControllerEditedImage] ?: info[UIImagePickerControllerOriginalImage];
CIImage*detectImage = [CIImage imageWithData:UIImagePNGRepresentation(pickedImage)];
//解析扫描二维码结果字符串
CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:@{CIDetectorAccuracy: CIDetectorAccuracyLow}];
CIQRCodeFeature*feature = (CIQRCodeFeature*)[detector featuresInImage:detectImage options:nil].firstObject;
[picker dismissViewControllerAnimated:YES completion:^{
if(feature.messageString) {
NSLog(@"=================二维码结果为%@",feature.messageString);
}else{
NSLog(@"未扫描到相应二维码");
}
//停止会话对象扫描
[self.session stopRunning];
//移除扫描层layer
[self.layer removeFromSuperlayer];
}];
}
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