A design patent, https://en.wikipedia.org/wiki/Design_patent, is different from a patent granted for an invention.

That was a design patent[1], which are different from normal patents. A design patent is a form of legal protection granted to the ornamental design of an article of manufacture. Design patents are a type of industrial design right.

Whether you think it is a valid design patent or not is a different question. There is no doubt that the outline of the iPhone was iconic, and Apple was trying to protect that, and Samsung was trying to ape it.

[1] https://en.wikipedia.org/wiki/Design_patent

Though that was a design patent, they also got a normal patent for the pythagorean formula (they didn’t invent pinch zoom, so they patented computing the distance between two fingers from two x,y coordinates).