在ios 中 扫瞄二维码，条形码基本有 2中第三方的库，一个是zbar 一个是zxing，zxing 在android中表现的比较出色，但是在ios 中不是很好用，扫瞄效率低，我们一般都用zbar，但是有些 条形码就是很奇葩，用zbar无法识别，下面就是一种

 我用了好多ios 的app 都无法识别， 《我查查》，《快拍二维码》，《微信》，自己用zbar都不行，最后用android 手机轻松扫瞄ok，哪我知道为什么了，是zxing可以搞定这种条形码。马上就换了zxing 来测试。 去github 找到了 zxing 的demo。但是悲剧的时无法识别各种条形码。

而且工程还报错。

  报Private field 'cached_y_' not used 编译通不过，解决办法就是

删除工程“buliding setting”的"Other Warning Flags"  的后面的参数：

"-Werror" ，  "-Wno-unused-parameter"  等等

  我在网上着了下原因 ，问题解决了。

方法是：

 1.修改 OverlayView.m文件中的61行左右

 co

注释掉下面代码

// self.oneDMode = isOneDModeEnabled;  

2.在ZXingWidgetController.m中用这个函数替换以前的函数

 也就是上面红色的部分做了修改

- (void)captureOutput:(AVCaptureOutput *)captureOutput   
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer   
       fromConnection:(AVCaptureConnection *)connection   
{  
  if (!decoding) {  
    return;  
  }  
  CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);   
  /*Lock the image buffer*/  
  CVPixelBufferLockBaseAddress(imageBuffer,0);   
  /*Get information about the image*/  
  size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);   
  size_t width = CVPixelBufferGetWidth(imageBuffer);   
  size_t height = CVPixelBufferGetHeight(imageBuffer);   
      
  uint8_t* baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);   
  void* free_me = 0;  
  if (true) { // iOS bug?  
    uint8_t* tmp = baseAddress;  
    int bytes = bytesPerRow*height;  
    free_me = baseAddress = (uint8_t*)malloc(bytes);  
    baseAddress[0] = 0xdb;  
    memcpy(baseAddress,tmp,bytes);  
  }  
  
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();   
  CGContextRef newContext =  
    CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace,  
                          kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst);   
  
  CGImageRef capture = CGBitmapContextCreateImage(newContext);   
  CVPixelBufferUnlockBaseAddress(imageBuffer,0);  
  free(free_me);  
  
  CGContextRelease(newContext);   
  CGColorSpaceRelease(colorSpace);  
  
  CGRect cropRect = [overlayView cropRect];  
  if (oneDMode) {  
    // let's just give the decoder a vertical band right above the red line  
<span style="color:#ff0000;">//    cropRect.origin.x = cropRect.origin.x + (cropRect.size.width / 2) - (ONE_D_BAND_HEIGHT + 1);  
//    cropRect.size.width = ONE_D_BAND_HEIGHT;  
//    // do a rotate  
//    CGImageRef croppedImg = CGImageCreateWithImageInRect(capture, cropRect);  
//    CGImageRelease(capture);  
//    capture = [self CGImageRotated90:croppedImg];  
//    capture = [self CGImageRotated180:capture];  
//    //              UIImageWriteToSavedPhotosAlbum([UIImage imageWithCGImage:capture], nil, nil, nil);  
//    CGImageRelease(croppedImg);  
//    CGImageRetain(capture);  
//    cropRect.origin.x = 0.0;  
//    cropRect.origin.y = 0.0;</span>  
    cropRect.size.width = CGImageGetWidth(capture);  
    cropRect.size.height = CGImageGetHeight(capture);  
  }  
  
  // N.B.  
  // - Won't work if the overlay becomes uncentered ...  
  // - iOS always takes videos in landscape  
  // - images are always 4x3; device is not  
  // - iOS uses virtual pixels for non-image stuff  
  
  {  
    float height = CGImageGetHeight(capture);  
    float width = CGImageGetWidth(capture);  
  
    CGRect screen = UIScreen.mainScreen.bounds;  
    float tmp = screen.size.width;  
    screen.size.width = screen.size.height;;  
    screen.size.height = tmp;  
  
    cropRect.origin.x = (width-cropRect.size.width)/2;  
    cropRect.origin.y = (height-cropRect.size.height)/2;  
  }  
  CGImageRef newImage = CGImageCreateWithImageInRect(capture, cropRect);  
  CGImageRelease(capture);  
<span style="color:#ff0000;"> // UIImage *scrn = [[UIImage alloc] initWithCGImage:newImage];  
    int backCameraImageOrientation = UIImageOrientationRight;  
    UIImage *scrn = [[UIImage alloc] initWithCGImage:newImage scale:  
                     (CGFloat)1.0 orientation:backCameraImageOrientation];  
</span>  
  CGImageRelease(newImage);  
  Decoder *d = [[Decoder alloc] init];  
  d.readers = readers;  
  d.delegate = self;  
  cropRect.origin.x = 0.0;    
  cropRect.origin.y = 0.0;  
  decoding = [d decodeImage:scrn cropRect:cropRect] == YES ? NO : YES;  
  [d release];  
  [scrn release];  
}   

3.在ViewController.mm 文件中做下面的修改

#import "MultiFormatOneDReader.h"  
  
- (void)pressButton1:(UIButton *)button  
{  
  <span style="color:#ff0000;">  ZXingWidgetController *widController = [[ZXingWidgetController alloc] initWithDelegate:self showCancel:YES OneDMode:YES];  
    NSMutableSet *readers = [[NSMutableSet alloc] init];  
    QRCodeReader *qrcodeReader = [[QRCodeReader alloc] init];  
  
    MultiFormatOneDReader *OneReaders=[[MultiFormatOneDReader alloc]init];  
   
    [readers addObject:qrcodeReader];  
     [readers addObject:OneReaders];</span>  
    widController.readers = readers;  
    [self presentViewController:widController animated:YES completion:^{}];  
}  

 看效果：

 二：

三：

四：