今天遇到個(gè)問題，通過iphone照相上傳的照片，后臺(tái)人員拿到是橫著的。還有，后臺(tái)同事說上傳的圖片是png的，但是實(shí)際上其實(shí)是jpg的，只是后綴名包了一層png。具體為什么，還有待我查查。先說翻轉(zhuǎn)問題，查了一下，解決方法有很多，下面就說一個(gè)給大家。
先說下原因：看論壇中的兄弟說，用相機(jī)拍攝出來的照片含有EXIF信息，UIImage的imageOrientation屬性指的就是EXIF中的orientation信息。
如果我們忽略orientation信息，而直接對(duì)照片進(jìn)行像素處理或者drawInRect等操作，得到的結(jié)果是翻轉(zhuǎn)或者旋轉(zhuǎn)90之后的樣子。這是因?yàn)槲覀儓?zhí)行像素處理或者drawInRect等操作之后，imageOrientaion信息被刪除了，imageOrientaion被重設(shè)為0，造成照片內(nèi)容和imageOrientaion不匹配。
所以，在對(duì)照片進(jìn)行處理之前，先將照片旋轉(zhuǎn)到正確的方向，并且返回的imageOrientaion為0。

下面是代碼實(shí)現(xiàn)：

• (UIImage *)fixOrientation:(UIImage *)aImage {
  if (aImage.imageOrientation == UIImageOrientationUp)
  return aImage;

  CGAffineTransform transform = CGAffineTransformIdentity;

  switch (aImage.imageOrientation) {
  case UIImageOrientationDown:
  case UIImageOrientationDownMirrored:
  transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
  transform = CGAffineTransformRotate(transform, M_PI);
  break;

    case UIImageOrientationLeft:
    case UIImageOrientationLeftMirrored:
        transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
        transform = CGAffineTransformRotate(transform, M_PI_2);
        break;
        
    case UIImageOrientationRight:
    case UIImageOrientationRightMirrored:
        transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
        transform = CGAffineTransformRotate(transform, -M_PI_2);
        break;
    default:
        break;
  

  }

  switch (aImage.imageOrientation) {
  case UIImageOrientationUpMirrored:
  case UIImageOrientationDownMirrored:
  transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
  transform = CGAffineTransformScale(transform, -1, 1);
  break;

    case UIImageOrientationLeftMirrored:
    case UIImageOrientationRightMirrored:
        transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);
        transform = CGAffineTransformScale(transform, -1, 1);
        break;
    default:
        break;
  

  }

  CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,
  CGImageGetBitsPerComponent(aImage.CGImage), 0,
  CGImageGetColorSpace(aImage.CGImage),
  CGImageGetBitmapInfo(aImage.CGImage));
  CGContextConcatCTM(ctx, transform);
  switch (aImage.imageOrientation) {
  case UIImageOrientationLeft:
  case UIImageOrientationLeftMirrored:
  case UIImageOrientationRight:
  case UIImageOrientationRightMirrored:
  // Grr...
  CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);
  break;

    default:
        CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.CGImage);
        break;
  

  }

  CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
  UIImage *img = [UIImage imageWithCGImage:cgimg];
  CGContextRelease(ctx);
  CGImageRelease(cgimg);
  return img;
  }

大家粘過去就可以直接用了。
不過有個(gè)問題就是
我是使用的UIImagePickerControllerEditedImage 而非
UIImagePickerControllerOriginalImage 等其他模式，具體原因?yàn)槭裁?，我還真就不知道。
希望對(duì)大家有用。