After the iPhoneX, I am really struggling with the image sizes and naming conventions which supports all devices. Is there any way to use 3x images for 4.7, 5.5 snd 5.8 screens? What are the exact dimensions I should use for an imageview in full screen?
You can use image with .pdf format. So you need to manage only single scale image with 1x. It will support all screen sizes so you don't need to mange 1x,2x,3x png. So single image can adjust all devices and also reduce app size.
You can follow these simple steps to implement this method:
Step 1: Get your background image with 1x size in .png format and convert it to .pdf file
Step 2: Add that .pdf image in your project's Assets.xcassets and make you have to select "Single scale" in asset property otherwise you can't add .pdf formatted image.
Step 3: Add set that image in imageview and check with different devices
Feel free to ask anything. :-)
来源：https://stackoverflow.com/questions/48483934/how-to-handle-iphone-screen-sizes-resolution-for-background-images