I initially tried to do the scaling myself with 2 games and it was just madness (scene size = view size or scene scale mode = .ResizeFill). You have to adjust all values e.g font size, sprite sizes, impulses etc for all devices and it will never be consistent.
So you have 2 options basically
1) Set scene size to 1024X768 (landscape) or 768×1024 (portrait). This was the default setting in Xcode 7.
You than usually just have/show some extra background at the top/bottom (landscape) or left/right (portrait) on iPads which gets cropped on iPhones.
Examples of games that show more on iPads / crop on iPhones:
Altos Adventure, Leos Fortune, Limbo, The Line Zen, Modern Combat 5.
2) Apple changed the default scene size in xCode 8 to iPhone 6/7 (7501334-Portait, 1337750-Landscape). This setting will crop your game on iPads.
Examples of games that show less on iPads:
Lumino City, Robot Unicorn Attack
Chosing between the 2 options is up to you and depends what game you are making. I usually prefer to use option 1 and show more background on iPads.
Regardless of scene size scale mode is usually best left at the default setting of .aspectFill.
To adjust specific things such as labels etc you can do it this way
if UIDevice.current.userInterfaceIdiom == .pad {
...
}
You can try the scene scaling yourself, create a new SpriteKit sample game project. Run on all iPhones and you will notice the HelloWorld label looks perfect on all devices.
Now change the default settings to scene size = frame or use .ResizeFill, the HelloWorld label is not scaled properly anymore on all devices.
As a side note, the line
if let scene = GameScene(fileNamed: "GameScene")
references the GameScene.sks file. You said you do everything programatically, therefore you can probably delete the GameScene.sks file and change the line to
let skView = view as! SKView!
let scene = GameScene(size: CGSize(width: 1024, height: 768)) // 768 x 1024 if portrait
Update:
I am now using a slightly different variant as I had problems adapting my game to iPhoneX. I set scene size to 1334×750 and use aspect fit as scale mode. I than run some code to remove the black bars if needed e.g. on iPads or iPhone X. It’s based on this great article (link no longer works).
http://endlesswavesoftware.com/blog/spritekit-skscene-scalemode/