This is sort of a newbie question, but I'm not a designer.

In iOS, we can make universal apps (i.e. support both iphone & iPad). But when it comes to background images' sizes I have NO idea what's the principle there.

For example, I have an idea for an app. It will be universal app. The login screen would have a full size image (or image that's stretched from size to size). The point is to make it look HD on different devices (from biggest iPad to smallest iphone)

Is there are some principles/rules to follow? What's the biggest size you make your full screen images?

Thank you

  • What resources have you looked at? What have you tried? – Zach Saucier Jun 26 '16 at 5:11
  • I tried to look into Apple's documentation and some blog posts but I didn't find anything significant. I'm trying to get the overall image of things, the main principles of app design and how it should be done – Dani Jun 26 '16 at 7:38

Honestly, it's up to you. Do whatever works. There are no Apple guidelines that I know of (and there are on most things) and any approach is valid.

Your basically have two options:

  • Use the same image in all cases.

    If your image is always going to cover the entire screen there will only be a small portion of the image visible on all devices as the edges will be cropped depending on the size of the device so keep that in mind if there are important elements in your image. You can also specify wether the image should scale to fill or fit its view or not scale at all etc.

  • Use device specific images.

    Using distinct images for specific devices gives you a lot more control over how your images are going to look but is a obviously a lot more work.

    There are a number of ways you can implement this in an app:

    • You can use size classes to show or hide views depending on the device size.
    • In Xcode, you can use asset catalogs to define your images, which help you manage the different sizes and resolutions and will always serve the correct images.
    • Or you can manually control the image loading in the app yourself based on whatever conditions you like: iOS version, device type or anything else.

What method[s] you use will completely depend on your situation, the images being used and what you want to achieve.

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