When you update apps in iOS 8, you may encounter an annoying glitch. The update process can freeze and not finish as it normally does. Forcing the app to close or temporarily removing it from the iPhone can help you work around this problem.
Force the App to Close
Double click the iPhone's Home button to bring up a list of recently used apps. Locate the app you want to close by swiping left and right.
Swipe up on the app you want to close.
Restart your iPhone by pressing the Sleep/Wake button until the Apple logo appears.
Enter the passcode when the iPhone prompts you for it.
Tap the App Store icon on the Home screen. Tap Updates and select your app from the Available Updates section..
Remove and Reinstall the App
Tap and hold any app icon on the Home screen until all the app icons begin jiggling.
Tap on the X on the app you want to delete.
Tap the Delete button when the iPhone prompts you to delete the app. Press the Home button to stop the jiggling apps.
Tap on the App Store icon on the Home screen. Select the Search icon and type the name of the app you deleted into the search field. Tap the app to download it and reinstall it on your iPhone.
Change the Automatic Updates Setting
Tap the Settings app to start it.
Tap iTunes & App Store.
Slide the Apps slider under the heading Automatic Downloads to change the setting. Turn it off if it's on and try to update manually, or turn it off, restart your iPhone and then turn the setting back on.
Update your apps in the App Store. Go the Updates section of the app to find available updates.