Xamarin iOS CGImageFromUrl returns null - ios

Question

I am using Xamarin iOS on windows Visual studio to extract metadata from a photo taken by the iphone camera.
private void GetMetaData(NSUrl url)
{
CGImageSource myImageSource;
myImageSource = CGImageSource.FromUrl(url, null);
var ns = new NSDictionary();
var imageProperties = myImageSource.CopyProperties(ns, 0);
var gps = imageProperties.ObjectForKey(CGImageProperties.GPSDictionary) as NSDictionary;
var lat = gps[CGImageProperties.GPSLatitude];
var latref = gps[CGImageProperties.GPSLatitudeRef];
var lon = gps[CGImageProperties.GPSLongitude];
var lonref = gps[CGImageProperties.GPSLongitudeRef];
var loc = String.Format("GPS: {0} {1}, {2} {3}", lat, latref, lon, lonref);
Console.WriteLine(loc);
}
the url being passed into the method is as:- {file:///var/mobile/Media/DCIM/100APPLE/IMG_0006.JPG}
The CGImageSource.FromUrl(url, null) returns null and my app crashes... Can anyone explain to me how I need to fix this?
Edit This is how I am getting the URL for the image.
protected void Handle_FinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs e)
{
NSUrl url = null;
try
{
void ImageData(PHAsset asset)
{
if (asset == null) throw new Exception("PHAsset is null");
PHImageManager.DefaultManager.RequestImageData(asset, null, (data, dataUti, orientation, info) =>
{
//Console.WriteLine(data);
Console.WriteLine(info);
url = info.ValueForKey(new NSString("PHImageFileURLKey")) as NSUrl;
// Call method to get MetaData from Image Url //
GetMetaData(url);
});
}

Answer 1

As I said in your last post: Xamarin iOS camera and photos: If you capture photos from camera, the event will not return a ReferenceUrl. But you can get the metadata info with another key:
protected void Handle_FinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs e)
{
var metadataInfo = e.Info["UIImagePickerControllerMediaMetadata"]; //or e.MediaMetadata;
}
This will contain some basic information which may be helpful to you. But this NSDictionary doesn't contain the GPS information. Because this picture is created by yourself, you should get the GPS by using CLLocationManager manually:
CLLocationManager manager;
manager = new CLLocationManager();
manager.RequestWhenInUseAuthorization();
manager.LocationsUpdated += (locationSender, e) =>
{
//get current locations
manager.StopUpdatingLocation();
};
manager.StartUpdatingLocation();
Please notice that add the keys in info.plist: NSLocationWhenInUseUsageDescription and NSLocationAlwaysAndWhenInUsageDescription on iOS11, if you want to deploy iOS10 add NSLocationAlwaysUsageDescription.
In this way, there's no need to get metadata from CGImageSource when you pick photos from camera.