What are the new Apple Watch "Home Screen" and "Short Look" image asset dimensions in Xcode 10?

Question

The new Apple Watch sizes for Series 4 are 40mm and 44mm, and Xcode 10 has provided new .xcassets image slots for them under "Home Screen" and "Short Look":

What are the optimal image dimensions for these 3 new assets?

Answer 1

Here are all the new sizes in order:

Home Screen (App Launcher)

40mm 2x: 88x88 pixels (44x44 logical pixels)
44mm 2x: 100x100 pixels (50x50 logical pixels)

Short Look (Quick Look)

40mm 2x: 196x196 pixels (98x98 logical pixels)
44mm 2x: 216x216 pixels (108x108 logical pixels)

---

How did I get this information?

If you select an image in an app icon set and open the Attributes inspector (the last icon on the right sidebar), you will get some information about the image, including its size:

If you navigate to AppIcon.appiconset/Contents.json inside the .xcassets file, you'll get a nice cheat sheet for all sizes:

[...]

{
  "size" : "44x44",
  "idiom" : "watch",
  "scale" : "2x",
  "role" : "appLauncher",
  "subtype" : "40mm"
},

[...]

{
  "size" : "50x50",
  "idiom" : "watch",
  "scale" : "2x",
  "role" : "appLauncher",
  "subtype" : "44mm"
},

[...]

{
  "size" : "98x98",
  "idiom" : "watch",
  "scale" : "2x",
  "role" : "quickLook",
  "subtype" : "42mm"
},
{
  "size" : "108x108",
  "idiom" : "watch",
  "scale" : "2x",
  "role" : "quickLook",
  "subtype" : "44mm"
},

[...]