Developer have to make a description in project "info.plist"if developer wanna to access user's photo library.

open info.plist , add a new item "Privacy - Photo Library Usage Description", it is a String. the value blank fill "Your usage description".

ps. If you want to use Xcode7 and iOS 10, You have to download Xcode8 beta. Then, find file Xcode8 -> Contents -> Developer -> Platforms -> iPhoneOS.platform -> DeviceSupport -> 10.0 (14A5261u) , copy the 10.0 (14A5261u) to Xcode7 document directory with the same path.finally, Xcode7 is going to complete the symbol file, just wait.

Download the iOS10 developer disk image:

developer disk image iOS10 for Xcode7