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iosiphonexcodeipadassets

Assets.xcassets - Universal not working

I am using Universal for Assets.xcassets in the hopes that I only have to create 3 different sizes for each image I use. But, despite Assets.xcassets telling me that my images are Universal in the Attributes Inspector, when I test on my iPad, the images are blurry and aren't as sharp as they are on my iPhone, making me question why there is a Universal option.

I've double checked all my images and they are all correctly sized.

My questions:

  1. In the Attributes Inspector, under Universal, there are iPhone and iPad options. In order for my iPad to provide crystal clear images, should I use the iPad option?
  2. And if I should: What's the point of the Universal option if it doesn't really do its job?
  3. Also if I should: What size images do I use. The iPad option gives me the options of 1x and 2x size images. So, should the size of the 1x image for iPad be the same size as 1x image for Universal?

Thanks in advance.

Solution

  • Universal merely means that this app will run on iPad and iPhone natively. Thus the devices on which your app might run can have a single-resolution, double-resolution, or triple-resolution screen.

    If you have checked Universal, accordingly, you should see three slots:

    enter image description here

    Your job, therefore, is to make three versions of your image, sized in proportion. If the 1x is 100x100, the 2x should be 200x200 and the 3x should be 300x300. The version in the appropriate slot will be used at runtime in accordance with the screen resolution of the device we're running on.

    The asset catalog does not do any image sizing for you. You have to do it beforehand. (I find Graphic Converter a nice utility for this purpose.)

    You could just supply a 3x image and allow the runtime to size down for you, but this is a waste of memory; Apple specifically advises against this in one of the WWDC 2016 videos. So just bite the bullet and make all three image sizes yourself.

    Finally:

    when I test on my iPad, the images are blurry and aren't as sharp as they are on my iPhone

    Hmm, the only reason I can think of for this is that your app is not running natively on the iPad, but is an iPhone app running in "emulation mode" on the iPad. If that's the case, nothing you can do is going to make it look really good. It would be better to write your app as a true Universal app. That is a setting that you make when you create the project initially (though it can be changed later by editing the app target).