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二维码的读取

读取二维码需要导入AVFoundation框架

利用摄像头识别二维码中的内容

1.输入(摄像头)

2.由会话将摄像头采集到的二维码图像转换成字符串数据

3.输出数据

4.由预览图层显示扫描场景

 

#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>

@interface ViewController ()<AVCaptureMetadataOutputObjectsDelegate>
@property (nonatomic, strong) AVCaptureSession *session;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;
@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

// 1. 实例化拍摄设备
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

// 2. 设置输入设备
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:nil];

// 3. 设置元数据输出
// 3.1 实例化拍摄元数据输出
AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
// 3.3 设置输出数据代理
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

// 4. 添加拍摄会话
// 4.1 实例化拍摄会话
AVCaptureSession *session = [[AVCaptureSession alloc] init];
// 4.2 添加会话输入
[session addInput:input];
// 4.3 添加会话输出
[session addOutput:output];
// 4.3 设置输出数据类型,需要将元数据输出添加到会话后,才能指定元数据类型,否则会报错
[output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];

self.session = session;

// 5. 视频预览图层
// 5.1 实例化预览图层, 传递_session是为了告诉图层将来显示什么内容
AVCaptureVideoPreviewLayer *preview = [AVCaptureVideoPreviewLayer layerWithSession:_session];

preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
preview.frame = self.view.bounds;
// 5.2 将图层插入当前视图
[self.view.layer insertSublayer:preview atIndex:100];

self.previewLayer = preview;

// 6. 启动会话
[_session startRunning];

}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{

// 会频繁的扫描,调用代理方法
// 1. 如果扫描完成,停止会话
[self.session stopRunning];
// 2. 删除预览图层
[self.previewLayer removeFromSuperlayer];

NSLog(@"%@", metadataObjects);
// 3. 设置界面显示扫描结果

if (metadataObjects.count > 0) {
AVMetadataMachineReadableCodeObject *obj = metadataObjects[0];
// 提示:如果需要对url或者名片等信息进行扫描,可以在此进行扩展!
// _label.text = obj.stringValue;
NSLog(@"%@", obj.stringValue);
}
}


@end

二维码的读取