參考文檔

在實(shí)際開發(fā)中，最方便的還是直接使用第三方如SYQRCodeViewController 和QRCodeReaderViewController。

ZBar

ZBar和ZXing都可以實(shí)現(xiàn)掃描二維碼，后者更可以生成二維碼，但兩者都已停止更新維護(hù)，并且iOS 8.0后系統(tǒng)也有了自己的二維碼生成的掃描。所以第三方就略顯尷尬,事實(shí)上原生API也是效率最高的。

#import <ZBarSDK.h>
@interface ViewController ()<ZBarReaderViewDelegate>
{
    ZBarReaderView *readerView;
}
@end

//當(dāng)然先要獲得獲得授權(quán)并判斷相機(jī)是否可用
- (IBAction)gogoAction:(UIButton *)sender {
    
    //初始化照相機(jī)窗口
    readerView = [[ZBarReaderView alloc]init];
    //設(shè)置代理
    readerView.readerDelegate = self;
    //自定義大小
    //readerView.frame = CGRectMake(100, 100, 300, 300);
    //設(shè)置掃描區(qū)域，標(biāo)準(zhǔn)坐標(biāo)。
    //如果要在readerView上添加控件最好再自定義一個(gè)透明view
    readerView.frame=self.view.bounds;
    self.readerView.scanCrop= CGRectMake(0.25,0.3,0.5,0.5）
   
    readerView.center = self.view.center;
    readerview.backgroundColor = [UIColor clearColor];
    readerview.torchMode = NO；//關(guān)閉閃光燈
    readerView.allowsPinchZoom = YES;//允許手勢(shì)變焦
     readerViewshowsFPS = YES;//顯示幀率

    //添加到父視圖
    [self.view addSubview:readerView];
    //二維碼/條形碼識(shí)別設(shè)置
    ZBarImageScanner *scanner = reader.scanner;
    [scanner setSymbology:ZBAR_I25
                   config:ZBAR_CFG_ENABLE
                       to:0];
    //必須啟動(dòng)
    [ readerView start];
  }

/*********ZBarReaderViewDelegate***********/
//掃描開始
-(void)readerViewDidStart:(ZBarReaderView *)readerView{
     readerView.hidden = NO;
}
//掃描停止
- (void) readerView: (ZBarReaderView*) readerView didStopWithError: (NSError*) error{
     readerView.hidden = YES;
}
//掃描到二維碼
- (void) readerView: (ZBarReaderView*) readerView  didReadSymbols: (ZBarSymbolSet*) symbols  fromImage: (UIImage*) image{

    //對(duì)掃描到的二維碼進(jìn)行解析
    ZBarSymbol *symbol = nil;
     for (symbol in symbols) {
        break;
     }
    NSString *text = symbol.data;
    NSLog(@"%@",text);
    
    //不停止的話會(huì)連續(xù)掃描
    [readerView stop];
}

AVFoundation

1. 導(dǎo)入庫文件
   AVFoundatio.framework CoreImage.framework
2. 代碼示例

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

@interface ViewController()<AVCaptureMetadataOutputObjectsDelegate>
//捕獲會(huì)話
@property (nonatomic,strong) AVCaptureSession *session;
//預(yù)覽圖層，可以通過輸出設(shè)備展示被捕獲的數(shù)據(jù)流。
@property (nonatomic,strong) AVCaptureVideoPreviewLayer *previewLayer;
@end

@implementation ViewController
- (IBAction)scanAction:(UIButton *)sender {
    //實(shí)例化拍攝設(shè)備
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    //設(shè)置輸出設(shè)備
    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (error)      return;//沒有照相機(jī)
   
    //實(shí)例化拍攝元數(shù)據(jù)輸出
    AVCaptureMetadataOutput *output=[[AVCaptureMetadataOutput alloc]init];
    //設(shè)置輸出數(shù)據(jù)代理
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    
    //實(shí)例化拍攝會(huì)話
    AVCaptureSession *session =[[AVCaptureSession alloc]init];
    [session setSessionPreset:AVCaptureSessionPresetHigh];//預(yù)設(shè)輸出質(zhì)量
    //添加會(huì)話輸入
    [session addInput:input];
    //添加會(huì)話輸出
    [session addOutput:output];
    //添加會(huì)話輸出條碼類型
    [output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];
    self.session = session;
    
    //實(shí)例化預(yù)覽圖層
    AVCaptureVideoPreviewLayer *preview = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
    //preview.frame = CGRectMake(0, 0, 300, 300);
    preview.frame = [UIScreen mainScreen].bounds;
    //將圖層插入當(dāng)前視圖
    [self.view.layer insertSublayer:preview atIndex:100];
    self.previewLayer = preview;
    
    //啟動(dòng)會(huì)話
    [_session startRunning];
  }

 //AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    // 會(huì)頻繁的掃描，調(diào)用代理方法
    // 1. 如果掃描完成，停止會(huì)話
    [self.session stopRunning];
    // 2. 刪除預(yù)覽圖層
    [self.previewLayer removeFromSuperlayer];
    // 3. 設(shè)置界面顯示掃描結(jié)果
    //判斷是否有數(shù)據(jù)
    NSString *str = nil;
    if (metadataObjects.count > 0) {
        AVMetadataMachineReadableCodeObject *obj = metadataObjects[0];
        //如果需要對(duì)url或者名片等信息進(jìn)行掃描，可以在此進(jìn)行擴(kuò)展
        str  = obj.stringValue;
        NSLog(@"%@",str);
    }
    //結(jié)束掃描
    [self dismissViewControllerAnimated:NO
                             completion:^{
        UIAlertController *alert = [UIAlertController alertControllerWithTitle:nil message:str preferredStyle:UIAlertControllerStyleAlert];
        UIAlertAction *action = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil];
        [alert addAction:action];
        [self presentViewController:alert animated:YES completion:nil];
    }];
}