• (void)createQR{
  // 1. 創(chuàng)建一個二維碼濾鏡實例(CIFilter)
  CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
  // 濾鏡恢復(fù)默認(rèn)設(shè)置
  [filter setDefaults];
  // 2. 給濾鏡添加數(shù)據(jù)
  NSString *string = [NSString stringWithFormat:@"http://www.lvlvchat.com/mobile/lvchatregister?from=%@",self.ID];
  NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
  // 使用KVC的方式給filter賦值
  [filter setValue:data forKeyPath:@"inputMessage"];

  // 3. 生成二維碼
  CIImage *image = [filter outputImage];

// _qrImg = [UIImage imageWithCIImage:image];
// 4. 顯示二維碼
_qrImg = [self createNonInterpolatedUIImageFormCIImage:image withSize:200];

//畫圖
UIGraphicsBeginImageContextWithOptions(_qrImg.size,NO,0.0);
[_qrImg drawInRect:CGRectMake(0, 0, _qrImg.size.width, _qrImg.size.height)];
UIImage *smallImage = [UIImage imageNamed:@"centerImg"];
[smallImage drawInRect:CGRectMake((_qrImg.size.width-KRate(50))/2, (_qrImg.size.width - KRate(50))/2, KRate(50), KRate(50))];
UIImage * finalImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

_qrImg = finalImage;

self.imageView.image = _qrImg;

}

• (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {

  CGRect extent = CGRectIntegral(image.extent);
  CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));

  // 1.創(chuàng)建bitmap;
  size_t width = CGRectGetWidth(extent) * scale;
  size_t height = CGRectGetHeight(extent) * scale;
  CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
  CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);
  CIContext *context = [CIContext contextWithOptions:nil];
  CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
  CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
  CGContextScaleCTM(bitmapRef, scale, scale);
  CGContextDrawImage(bitmapRef, extent, bitmapImage);

  // 2.保存bitmap到圖片
  CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
  CGContextRelease(bitmapRef);
  CGImageRelease(bitmapImage);

  UIImage *img = [UIImage imageWithCGImage:scaledImage];

  return img;
  }