Why use normal, @2x and @3x size images in iPhone when you can use only @3x and set the constraints in different size classes?

Question

我对此话题感到困惑。

Answer 1

Resizing images has a couple of costs including:

Scaling images is an imperfect process. A 3x image scaled to 1x pixel density can have visual artifacts or fail to communicate it's purpose to the user effectively.

Scaling images requires you to load the full size image on older devices with less memory and computing power available to perform those operations which can lead to slower performance. Especially during animations like scrolling views.

As always consider if these are concerns for your specific use case and act accordingly.