Question

I am attempting to save and load a UIImage to and from the iPhone documents directory after the image is picked from the iPhone Photo Library. It is able to do so, but for some reason, when I load the image, it rotates it 90 degrees counterclockwise. Here is my saveImage and loadImage methods:

Save Image:

- (void)saveImage: (UIImage*)image{
if (image != nil)
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                                                         NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString* path = [documentsDirectory stringByAppendingPathComponent: 
                      [NSString stringWithString: @"lePhoto.png"] ];
    //NSData* data = UIImagePNGRepresentation(image);
    //[data writeToFile:path atomically:YES];
    [UIImagePNGRepresentation(image) writeToFile:path atomically:YES];
    }
}

Load Image:

- (NSData*)loadImage{

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                                                         NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString* path = [documentsDirectory stringByAppendingPathComponent: 
                  [NSString stringWithString: @"lePhoto.png"] ];
NSData *data = [[NSData alloc] initWithContentsOfFile:path];


//UIImage *image = [[UIImage alloc] initWithData:data];   //my second try
//UIImage* image = [UIImage imageWithContentsOfFile:path];   //first try
//return image;
return data;
[data release];
}

And I am now loading the image like this, to see if it would, for some crazy reason, solve my problem (it didn’t, obviously):

UIImage* theImage = [[UIImage alloc] initWithData:[self loadImage]];

I have done some testing where I have two UIImageViews side-by-side, one on the left that doesn’t save and load the image before display (it just straight-up shows the image once a photo is picked from the ImagePicker), and one on the right that displays AFTER the save load occurs. The one on the right is the only one rotating 90 degrees CCW; the non Save/Load picture is displaying correctly. This only occurs on the actual iPhone. The simulator shows both images correctly. I have spent many, many hours attempting to figure it out, but to no avail. Any ideas as to what could be causing this?

EDIT: It should also be known that the image always says it’s oriented up, even when it obviously isn’t! It only rotates after ALL of the code has been run. I’ve tried doing a force redraw in between my code to see if that changes things, but it doesn’t (though it is possible I’m even doing that wrong. Who knows, anymore).
Also, it will not autorotate photos that have been screenshot from the iPhone. Only photos that have been taken by the camera. [I haven’t tried downloaded photos.] It’s the weirdest thing…

And if you’re wondering exactly how I’m pulling my picture, here’s the method that will at least shed light on what I’m doing (it’s not every method needed to do this function, obviously, but it gives insight on how I’ve written my code):

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { 
theimageView.image = [info objectForKey:@"UIImagePickerControllerOriginalImage"]; 
[self saveImage:[info objectForKey:@"UIImagePickerControllerOriginalImage"]]; 
[picker dismissModalViewControllerAnimated:YES]; 
}

Any advice is greatly appreciated. And I do know this much: if there’s a way to do something crazy to get some stupid, never-before-heard-of problem, chances are, I’ll find it, apparently 😛

Answer 1

Ok. I figured it out. Apparently when you save things with PNG representation, and not JPEG representation, the image orientation information is not saved with it. Because of this, every image loaded will default to showing orientation up. So, the easiest way is to do this:

NSData* data = UIImageJPEGRepresentation(image,0.0);
[data writeToFile:path atomically:YES];

instead of this:

[UIImagePNGRepresentation(image) writeToFile:path atomically:YES];

And, of course, changing all the picture names from .png to .jpg. The 0.0 part of the code above is to control Alpha levels, which is required of jpegs. Hope this helps people in the future!