Dealing with different iOS device resolutions in SpriteKit

Question

I'm playing around with SpriteKit in Xcode 6, iOS 8 beta 5. Everything is all laid out and working perfectly on the iPhone 4S simulator, however when switching to the 5S, the elements at the bottom of the screen are cut off.

It was to my understanding that the bottom left corner of the iPhone screen should be CGPoint(0, 0) but after checking the location by printing the coordinates to the console that the lowest point of the left corner I could click was around (5, 44). Is there something wrong in my scene setup thats causing this?

No changes have been made to the GameViewController file and even after I strip the GameScene file the problem persists.

Can anyone at least point me in the right direction with this?

Answer 1

Adding the following code will fix your problem (code is in Swift):

scene.scaleMode = SKSceneScaleMode.ResizeFill 

Now if you want to know why this fixes your problem, what your problem actually is, and how to handle multiple resolutions – I suggest you continue reading.

There are three things that can impact the position of nodes in your scene.

1) Anchor Point
Make sure your scene's anchor point is set to (0,0) bottom left. By default the scene's anchor point starts at (0,0) so i'm assuming that is not causing the issue.

2) Size
Check the size of your scene. I typically make my scene size match the size of the device (i.e. iPad, iPhone 4-inch, iPhone 3.5 inch), then I place another layer in the scene for storing my nodes. This makes me able to do a scrolling effect for devices with smaller resolutions, but it depends on your game of-course. My guess is that your scene size might be set to 320, 480 which could be causing the positioning problems on your iPhone 5s.

3) Scale Mode
The scale mode has a huge effect on the positioning of nodes in your scene. Make sure you set the scale mode to something that makes sense for your game. The scale mode kicks in when your scene size does not match the size of the view. So the purpose of the scale mode is to let Sprite Kit know how to deal with this situation. My guess is that you have the scene size set to 320,480 and the scene is being scaled to match the iPhone 5 view which will cause positioning problems identical to what you described. Below are the various scale modes you can set for your scene.

SKSceneScaleMode.AspectFill 

The scaling factor of each dimension is calculated and the larger of the two is chosen. Each axis of the scene is scaled by the same scaling factor. This guarantees that the entire area of the view is filled, but may cause parts of the scene to be cropped.

SKSceneScaleMode.AspectFit 

The scaling factor of each dimension is calculated and the smaller of the two is chosen. Each axis of the scene is scaled by the same scaling factor. This guarantees that the entire scene is visible, but may require letterboxing in the view.

SKSceneScaleMode.Fill 

Each axis of the scene is scaled independently so that each axis in the scene exactly maps to the length of that axis in the view.

SKSceneScaleMode.ResizeFill 

The scene is not scaled to match the view. Instead, the scene is automatically resized so that its dimensions always matches those of the view.

Conclusion
It looks like you want to remove the scaling of your scene, that way your positions in the scene will match the actual positions in the view. You can either set your scene's size to match the view size, in which case no scaling will take place. Or you can set your scene's scale mode to ResizeFill which will always make the scene's size match your view's size and it won't scale anything. In general I would stay away from any scaling and instead adjust the interface and the scene size to best suit each device. You may also want to add zoom and/or scrolling to allow devices with smaller resolutions to achieve the same view field.

---

But what if I want to scale my scene?
If however you need to scale your scene, but you still want positions to be relative to the view (i.e. You want (0,0) to be the bottom left of screen even when scene is cutoff) then see my answer here

---

Additional Info
See answer here for sample code showing how I layout nodes dynamically.

See answer here for more details about scaling to support multiple devices.