Design layout for Android and iOS, dimensions and resolution?

Question

Design

I make the first design for a mobile application for iOS and Android, I do it in Photoshop. I found a couple of excellent articles about screen density, but I just can’t figure out the dimensions completely:
Help. What size and resolution to start with?
Android devices have a huge number of screen sizes. iOS is easier. Confused. The following categories of devices should be covered:

• ipad
• iphone
• android mobile
• android tablet

Help understand.

Answer 1

everything is a little simpler as for me:
- since we have screens with very different pixel densities, it’s easier to just draw everything in a vector and save two or three options when cutting, such as x1, x2, x3
- since there are a lot of resolutions, it’s easier to choose a minimum size (320 * 480 for example) and maximum (for example, take the resolution of some iPad, naturally in virtual pixels and not 2500 or something there). For convenience, you can start drawing everything from the middle and then squeeze for the minimum and stretch for the maximum.
Well, do not forget that iOS and Android have slightly different guidelines. They are well worth reading.

Answer 2

In such cases, Sketch is very useful, especially now everyone has moved away from skeuomorphism towards flat design, which fits the vector very well.
But it's only for Mac, yes. But there is immediately an export to x2, x0.5, etc.
And a bunch of all sorts of UI templates, if you look - OS 7, Material Design, that's it.