Timestamp resolution for iPhone photos

iPhone photos have a timestamp that is displayed to the minute, but is there any way to see seconds or fractional seconds? Either using the native apps or with a purchased app?

If the internal timestamp is only to the minute, is there some other agency that helps the phone sort multiple photos taken within the same minute into chronological order?

I know, I could include a clock in the scene when I take the photo. Just wondering, especially for situations where that’s hard to do.

Thanks!

It should be stored with precision of at least 1 second. You can see the stored EXIF data with various free apps from the App Store, or on your computer with Preview/iPhoto (Mac) or Explorer (Windows).