Instagram users rejoice: you can now share photos and videos directly to the service from any other app that supports share extensions. The ability to share to Instagram from any other app comes courtesy of the app's new share extension, which has been highly requested feature since share extension support was added for third-party apps in iOS 8.
In order to get started, you'll first have to add Instagram to your share sheet. To do so, open a photo app of your choice and tap the Share button. From there, swipe to the far right on the row of app icons and tap the "More" button. Then, simply scroll down to Instagram and toggle the switch to the "On" position. From now on, Instagram will show as an available option for sharing photos from other apps.
Reposted from iMore.com