Nil pointer returned for [exifData tagValue:]

I'm trying to read EXIF data from pictures taken with the apple camera's application, containning EXIF informations. I use iphone-exif library available at http://code.google.com/p/iphone-exif/.

My problem is that I succes getting tag informations with [exifData tagDefinition:] function :

EXFTag* tag = [exifData tagDefinition:[NSNumber numberWithInt:EXIF_ExposureTime]];

Tag information are开发者_运维知识库 correctly displayed in console :

tag name : ExposureTime

tag dataType : 5

tag ID : 33434

tag components : 1

tag adress : 0x15f900

but I can't get the tag value :

id value = [exifData tagValue: [NSNumber numberWithInt:EXIF_ExposureTime]];

I get nil pointer :

value adress : 0x0 value size : 4 value content : 0

Results are exactly the same with other tag ID like ISO Speed ratings or Focal Length.

Do I made something wrong? Is the library dysfunctional?

Raphael

If you are using the UIImagePickerController then you will not have exif data. I tried this also.

Here is more information: UIImagePickerController and extracting EXIF data from existing photos

There is no solution. As said mracoker, if I use UIImagePickerController to take pictures OR to open pictures from user's photo album, no EXIF informations are included. That's realy bad for my proffesional training... :'(