iOS拍照后图片自动旋转90度的完美解决方法

今天开发一个拍照获取照片的功能的时候, 发现上传之后图片会自动旋转90.

测试发现, 只要是图片大于2m, 系统就会自动翻转照片

  相机拍照后直接取出来的uiimage（用uiimagepickercontrolleroriginalimage取出），它本身的imageorientation属性是3，即uiimageorientationright。如果这个图片直接使用则没事，但是如果对它进行裁剪、缩放等操作后，它的这个imageorientation属性会变成0。此时这张图片用在别的地方就会发生旋转。imageorientation是只读的，不能直接修改其值。

解决方法如下:

1. 设置相机的一个属性allowsediting为yes，设了这个值，你拍完照片后会在照片上出现一个框框，这就是对照片的裁剪编辑。在相机的代理方法中取照片的时候就别用uiimagepickercontrolleroriginalimage来取了，要用uiimagepickercontrollereditedimage。用这个key取出来的照片，它的imageorientation是0，所以之后的任何裁剪、缩放操作都不会造成旋转。这是第一种方法。

2. 第一种解决方法基本没用, 开发中基本都会对图片进行裁剪和压缩. 这里有一个专门针对这个事的很好的category

+ (uiimage *)fixorientation:(uiimage *)aimage {
  // no-op if the orientation is already correct
  if (aimage.imageorientation ==uiimageorientationup)
    return aimage;
  // we need to calculate the proper transformation to make the image upright.
  // we do it in 2 steps: rotate if left/right/down, and then flip if mirrored.
  cgaffinetransform transform =cgaffinetransformidentity;
  switch (aimage.imageorientation) {
    caseuiimageorientationdown:
    caseuiimageorientationdownmirrored:
      transform = cgaffinetransformtranslate(transform, aimage.size.width, aimage.size.height);
      transform = cgaffinetransformrotate(transform, m_pi);
      break;
    caseuiimageorientationleft:
    caseuiimageorientationleftmirrored:
      transform = cgaffinetransformtranslate(transform, aimage.size.width,0);
      transform = cgaffinetransformrotate(transform, m_pi_2);
      break;
    caseuiimageorientationright:
    caseuiimageorientationrightmirrored:
      transform = cgaffinetransformtranslate(transform, 0, aimage.size.height);
      transform = cgaffinetransformrotate(transform, -m_pi_2);
      break;
    default:
      break;
  }
  switch (aimage.imageorientation) {
    caseuiimageorientationupmirrored:
    caseuiimageorientationdownmirrored:
      transform = cgaffinetransformtranslate(transform, aimage.size.width,0);
      transform = cgaffinetransformscale(transform, -1, 1);
      break;
    caseuiimageorientationleftmirrored:
    caseuiimageorientationrightmirrored:
      transform = cgaffinetransformtranslate(transform, aimage.size.height,0);
      transform = cgaffinetransformscale(transform, -1, 1);
      break;
    default:
      break;
  }
  // now we draw the underlying cgimage into a new context, applying the transform
  // calculated above.
  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) {
    caseuiimageorientationleft:
    caseuiimageorientationleftmirrored:
    caseuiimageorientationright:
    caseuiimageorientationrightmirrored:
      // 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;
  }
  // and now we just create a new uiimage from the drawing context
  cgimageref cgimg =cgbitmapcontextcreateimage(ctx);
  uiimage *img = [uiimageimagewithcgimage:cgimg];
  cgcontextrelease(ctx);
  cgimagerelease(cgimg);
  return img;
}

以上所述是小编给大家介绍的ios拍照后图片自动旋转90度的完美解决方法，希望对大家有所帮助