iOS UIView scrolling UI - how to implement?
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Forgive me to the obtuse title, as I'm unsure how to describe this question.

Recently many iOS apps utilise a scrolling UI design pattern which helps to maximise screen real-estate, typically hiding the header when the user scrolls downwards.

For example, Instragram's main view has the Instragram header at the top. Scrolling upwards on this view keeps the header fixed at the top, and the view bounces back normally to the top of the content. But scroll down and the header acts as part of the content, making way for an extra 44 points of vertical space.

Its probably that I haven't done much iOS work in a while, but I can't easily figure out how best to impliment this? Apologies for the terrible description.