iOS 8, PhotoKit, PHAsset, unique identifier

Question

Working on an app that is iOS 8, and handles a lot of photos, I need to uniquely identify PHassets but cannot find any property to use? I found one property on

 PHObject/localIdentifier

documented here

https://developer.apple.com/library/ios/documentation/Photos/Reference/PHObject_Class/index.html#//apple_ref/occ/instp/PHObject/localIdentifier

Is there any way to have a unique ID on PHAsset? PHObject is a bit heavier to use.

Answer 1

Yes, that's the only property to use.

However, PHObject implements both -hash and -isEqual: methods. It also conforms to NSCopying protocol, which means that it can be used as a key in dictionaries and can be put in sets, etc. It also continues to work when you reload PHAsset objects. This is a huge win over ALAsset class. The implementation of -isEqual is much faster than the localIdentifier property and can be safely used on the main thread. You could use profiler to get an idea of what's under the hood.