问题
i was currently in to an app development and i have added a launcher screen in JPEG format which is displayed both in simulator and device .. but does it create any problem with apple approval guidelines ?
回答1:
Update for iOS 8+: you can now use XIB-based launch assets, which is by far the best approach to reduce file size and re-use the same assets for multiple screens sizes. Also, since XIBs support JPG assets, you can always embed JPGs onto XIB files now too!
The Apple documentation pre iOS 8 (now removed), explicitly stated that only PNG is allowed for the launch image:
App Launch (Default) Images
Every app must provide at least one launch image. This image is typically in a file named Default.png that displays your app’s initial screen in a portrait orientation. However, you can also provide other launch images to be used under different launch conditions. All launch images must be PNG files and must reside in the top level of your app’s bundle directory. (Avoid using interlaced PNGs.)
I can't speak to how accurate this document is, but it seems they are pretty specific on this point.
My advice: use 8-bit PNG's, and if your files are getting to big, simply don't include the @2x versions for the retina iPad. The 1x version upscales reasonably well on the retina iPad, and better than bloating your app by 5MB+
回答2:
Yes ofcourse you can use JPEG image in Launch screen or anywhere in project.NO it absolutely does not create any problems in approval process of Apple.So go ahead and code!
回答3:
Use a png if you can; not only is png artwork better visually, but iOS is optimised for png files.
While it is true Apple won't reject your app for using a jpeg, your users might.
回答4:
NO you should not use jpgs
Here are apple recomendations
Note: For all images and icons, the PNG format is recommended. The standard bit depth for icons and images is 24 bits (8 bits each for red, green, and blue), plus an 8-bit alpha channel. You do not need to constrain your palette to web-safe colors. Although you can use alpha transparency in the icons you create for navigation bars, toolbars, and tab bars, do not use it in application icons.
回答5:
You can only use PNG files for the launch images. Here is the proof.
回答6:
Yes , you can choose any one from JPEG/PNG.There is no guidelines from apple to choose type of image.
For more information you can follow apple launch image guidelines.
but I assume that PNGs are more preferable because Apple seems to use PNGs virtually everywhere in iPhone OS.
来源：https://stackoverflow.com/questions/4593236/can-i-use-a-jpeg-image-for-launching-screen