I am working on a template for an iPhone App and was wondering what dpi resolution is used for it ? 300 or 72 ?
I am not sure and I hope somebody can answer me that question.
iPhones
iPhone 1/3G/3GS 320 x 480 163 ppi
iPhone 4/4S 640 x 940 326 ppi
iPhone 5/5C/5S 640 x 1136 326 ppi
iPhone 6/6S 750 x 1334 326 ppi
iPhone 6 Plus/6S Plus 1080 x 1920 401 ppi
Without downsampling: 1242 x 2208 461 ppi
Except for the 6th generation (= 5th) iPod touch,
all the models are equal to their iPhone counterparts
iPads
iPad 1/2 768 x 1024 132 ppi
iPad 3/4/Air/Air 2 1536 x 2048 264 ppi
iPad Mini 1 768 x 1024 163 ppi
iPad Mini 2/3/4 1536 x 2048 326 ppi
iPad Pro 2737 x 2048 264 ppi
Apple Watches
Apple Watch 38 mm 272 x 340 326 ppi
Apple Watch 42 mm 312 x 390 326 ppi
The original iPhone screen has a resolution of 163dpi - use that in your template if you want to be able to print your screen designs at actual size.
72 is the dpi for images
Given the difference in the dpi between the iPhone and the simulator, you might want to use the raw pixel values of 480x320 for the iPhone screen.
The iPhone screen has 163 DPI, but I've found that images at that resolution appear too small in Xcode and Interface Builder. I recommend pretending that the screen has 72 DPI when making bitmap images for the iPhone, but remember that the screen has 163 DPI if you're drawing a ruler.
来源：https://stackoverflow.com/questions/1365112/what-dpi-resolution-is-used-for-an-iphone-app