'Popovers' to highlight areas of interest or new features?

I've noticed a lot of apps have a 'popover' that highlights areas of interest or new features (see pic for example).

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What are these called? I dont believe there is a ready made solution to these in Apple docs apart from iPad UIPopoverController.

Sorry if this seems a bit subjective but I am unsure of what its called.

Would love if someone could point me in a right direction.

Solution

That's definitely a custom implementation. I figure they would be called tool tips or speech bubbles if describing them to someone.