writeImageToSavedPhotosAlbum:metadata:completionBlock: - iphone

Question

I use the method writeImageToSavedPhotosAlbum:metadata:completionBlock: save taken picture to photo album,code is:
-(void)savePhotoToAlbum{
CGImageRef imageRef=[imageView image].CGImage;
NSDictionary *currentDic=[self getLocation];
NSDictionary *metadata=[NSDictionary dictionaryWithDictionary:currentDic];
ALAssetsLibrary *library=[[ALAssetsLibrary alloc] init];
[library writeImageToSavedPhotosAlbum:imageRef metadata:metadata completionBlock:^(NSURL *assetURL,NSError *error){
if(error == nil)
{
UIAlertView *alertView=[[UIAlertView alloc] initWithTitle:nil message:#"Save success!" delegate:nil cancelButtonTitle:#"Okay" otherButtonTitles:nil];
[alertView show];
[alertView release];
}
else
{
UIAlertView *alertView=[[UIAlertView alloc] initWithTitle:nil message:#"Save failure!" delegate:nil cancelButtonTitle:#"Okay" otherButtonTitles:nil];
[alertView show];
[alertView release];
}
}];
[library release];
}
.The method getLocation that is get user's current location!That can save success!Then I want to pick taken picture from photo album use UIImagePickerController! Code is :
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{ if([picker sourceType]==UIImagePickerControllerSourceTypeSavedPhotosAlbum)//picker image delegate
{
NSString *mediaType=[info objectForKey:UIImagePickerControllerMediaType];
if([mediaType isEqualToString:#"public.image"])
{
NSDictionary *metadata=[info objectForKey:UIImagePickerControllerMediaMetadata];
NSLog(#"%#",metadata);
}
}
}
Then log the metadata is null.That's why? And how do I get the metadata info which I saved?Thanks!

Answer 1

The metadata of the image will be available only if the sourceType is UIImagePickerControllerSourceTypeCamera.
See Ref. Look at the last paragraph in that page.

Answer 2

You can take log of metadata with AssetsLibrary framework:
-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
...
NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
if ([mediaType isEqualToString:(NSString*)kUTTypeImage]) {
NSURL *url = [info objectForKey:UIImagePickerControllerReferenceURL];
if (url) {
ALAssetsLibraryAssetForURLResultBlock resultblock = ^(ALAsset *myasset) {
CLLocation *location = [myasset valueForProperty:ALAssetPropertyLocation];
NSLog(#"\n\n\n____________________________\n");
NSLog(#"ORIENTATION: %#\n",[myasset valueForProperty:ALAssetPropertyOrientation]);
NSLog(#"LOCATION: %#\n",[myasset valueForProperty:ALAssetPropertyLocation]);
NSLog(#"DATE: %#\n",[myasset valueForProperty:ALAssetPropertyDate]);
NSLog(#"Duration: %#\n",[myasset valueForProperty:ALAssetPropertyDuration]);
NSLog(#"TYPE: %#\n",[myasset valueForProperty:ALAssetPropertyType]);
NSLog(#"\n____________________________\n\n\n");
//take coordinates only
CLLocationCoordinate2D coordinate = [location coordinate];
strCoord = [NSString stringWithFormat:#"long: %f; lat: %f;", coordinate.latitude, coordinate.longitude];
NSLog(#"%#", strCoord);
// location contains lat/long, timestamp, etc
// extracting the image is more tricky and 5.x beta ALAssetRepresentation has bugs!
};
ALAssetsLibraryAccessFailureBlock failureblock = ^(NSError *myerror) {
NSLog(#"cant get image - %#", [myerror localizedDescription]);
};
ALAssetsLibrary *assetsLib = [[ALAssetsLibrary alloc] init];
[assetsLib assetForURL:url resultBlock:resultblock failureBlock:failureblock];
}
}
...
}