Take screenshot in iPhone Simulator in Xcode 9

I have met the similar problem and here is the solution. Uncheck "Optimize Rendering for Window Scale" option from "Debug" menu.Then take your screenshot(Cmnd + S) with zoom. Now it will be in size 1242 x 2208

Use ⌘ + S to capture a screen shot.
(Use window + s, if you are using windows/non-apple keyboard).

See for more details: How to change simulator scale options with Xcode 9+.

Tip 1: How do you get screen shot with 100% (a scale with actual device size) that can be uploaded on AppStore?

Disable Optimize Rendering for Window scale from Debug menu, before you take a screen shot.

Here is an option

Menubar ▶ Debug ▶ Disable "Optimize Rendering for Window scale"

Tip 2: How to take a screen shot with Device Bezel?

Enable Show Device Bezel from Window menu.

Here is an option

Menubar ▶ Window ▶ Enable "Show Device Bezel"

Now,

1. Press ⌘ + shift + 4 + Spacebar, all together in Mac Keyboard. (A window snap capture mode will become active)
2. Select Simulator window/frame, that you want to capture. It will save screenshot with device bezel (with shadow effect in background) on (logged-in user's) desktop.

I tried and can take screenshot of size 1242 x 2208(required for App Store) from iPhone 8 Plus simulator in XCode 9.0 by steps below.

• Open your simulator
• Double click on toolbar of your simulator
• Command + S

The saved screenshot will have right dimensions. It works with every simuator.