Background fetch actually provides a solution this exact use case. If the user uses your app enough for iOS to let you run in time, the app should be able to "get ready" before the user opens it.
How so? You can know all the state you want, but iOS is still going to display that one static image. If the user is returning from background into a photo gallery, it's still going to show your default image. If the user is opening the app directly into a conversation, it's still going to show your default image.
