Screen Size:
Normal screen 320 pixel x 480 pixel IPhone 1, 3G, 3gs,ipod
Touch 1, 2, 3
3:2 Retina 960 pixel x 640 pixel IPhone 4, 4s,ipod touch 4
16:9 Retina 1136 pixel x 640 pixel iPhone 5,iphone 5S, iphone5c, ipod touch 5
Ipad
Normal screen 1024 pixel x 768 pixel IPad 1, Ipad2,ipad Mini
Retina screen 2048 pixel x 1536 pixel New ipad,ipad 4, ipad Air, ipad mini2
To facilitate developer development, the unified use point in IOS describes the size of the interface element.
So for one and a two, the iphone development can only be the size of the screen as the x 480 points for the development of the point and pixel conversion relationship is as follows:
Pu 1 point = 1 pixel
Retina Screen 1 point = 2 pixel
The same goes for development on the IPad, which can only be developed based on 768 x 1024.
On the IPhone 5 and ipod Touch 5 machine, for developers, its interface size is x 568 point, you only need to adjust the size of your interface (if you need to adjust).
For example: I have a button, to put in the middle of the screen position, then in the interface size of the 480 point device, just set its center for (320/2, 480/2) position can be, in the 3:2 Retina screen System This button can also be displayed correctly in the middle;
On a device with a screen size of 568 dots, you set its center as (320/2, 568/2).
You can get the base resolution of the current screen directly through [[UIScreen mainscreen] bounds], so you don't have to hard code.