Recently a colleague had just got a new iPhone 5 with iOS 6, but once she had upgraded she could no longer use the Tesco photo print application.
When ever the application loaded it gave the prompt that it would like to access your photos, with the usual Allow/Don't Allow, but they were greyed out, you could not press the buttons, it was very strange, it was like they were in the background. If you left the application for a while trying to work it out then the phone would freeze up and you could not quit out and had to reset the phone.
I looked into the settings to see if the Privacy tab was switched to off, and to rule out that this was causing a problem, this was not set. Next I tried to uninstall and reinstall the application, again this did not resolve the issue.
I tried to load the application once more, but as soon as the dialog appeared I double clicked the home button and selected the settings app, I was hoping that I would be able to switch apps then kill the Tesco app before the phone hung up again. As soon as I switched to the settings up the box was there so I could then click on Allow the application to access the photos.
After I had done this, the application worked as it should. So if there are other applications where you see this behaviour, double clicking the home button quickly and switching application may make the dialog available.
I am always interested in your thoughts so if you have any comments or feedback then please feel free to add any comments, or you can mail me here.