With the current library I am using for Android, I do something like this:

writeCharacteristic(callback1).enqueue()
waitForNotification(callback1).enqueue()

I don't have a general callback for notifications.

This is nice because I am interested in the value only after writes, I can use a different callback for different messages to keep things organized and I can put a lot of these in a queue and nothing gets mixed up.

Is it possibly to do something like this on iOS?