This has been asked multiple times here, but without a solid and understandable answer. This is a web-app, not a native-app.
I'm using:
<link rel="apple-touch-startup-image" href="images/startup.png" />
to display the startup image. It loads fine if the image's resolution is 320x460. I tried using the retina's resolution which is 640x920 (40px are taken out by the status bar), that didn't work. I've tried the @2x thing, that failed too.
Is it even possible [yet]?
This will add a Splash Screen to your Web App. Below are the sizes you’ll need for both iPad and iPhone/iPod Touch, these include the status bar area as well.
<!-- iPhone -->
<link href="http://www.example.com/mobile/images/apple-startup-iPhone.jpg" media="(device-width: 320px) and (device-height: 480px) and (-webkit-device-pixel-ratio: 1)" rel="apple-touch-startup-image">
<!-- iPhone (Retina) -->
<link href="http://www.example.com/mobile/images/apple-startup-iPhone-RETINA.jpg" media="(device-width: 320px) and (device-height: 480px) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">
<!-- iPhone 5 -->
<link href="http://www.example.com/mobile/images/apple-startup-iPhone-Tall-RETINA.jpg" media="(device-width: 320px) and (device-height: 568px) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">
<!-- iPad Portrait -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-Portrait.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: portrait) and (-webkit-device-pixel-ratio: 1)" rel="apple-touch-startup-image">
<!-- iPad Landscape -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-Landscape.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 1)" rel="apple-touch-startup-image">
<!-- iPad Portrait (Retina) -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-RETINA-Portrait.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: portrait) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">
<!-- iPad Landscape (Retina) -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-RETINA-Landscape.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">
If creating a Web App for iPad compatibility it’s recommended that both Landscape and Portrait sizes are used.