After reading:
Multiple "apple-touch-startup-image" resolutions for iOS web app (esp. for iPad)?
In that post's comments, Marconi's 'definitive' solution uses:
apple-touch-startup-image-2048x1496.png in:
<!-- iPad (Retina, landscape) SPLASHSCREEN-->
<link href="apple-touch-startup-image-2048x1496.png" media="(device-width: 1536px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">
uses:
apple-launch-1536x2048.png in:
<!-- iPad Mini, Air (1536px x 2048px) -->
<link rel="apple-touch-startup-image" media="(device-width: 768px) and (device-height: 1024px) and (-webkit-device-pixel-ratio: 2)" href="/apple-launch-1536x2048.png">
(a 40px difference)
Further, the medium article says the png has to be the "exact same resolution as the iOS device that uses the app". And the article also doesn't mention portrait/landscape orientation? Is that media query now redundant?
Can anyone share a tested 2018 solution that includes portrait/landscape orientation and all iPhones and iPads?