iOS determines whether the screen displays @2x or @3x to call the font size

The traditional font size adaptation may fit according to the width of the screen with a ratio of iphone5 or iphone6 width. But if there is a need to display a font on the phone that displays the @2x picture, another fixed-size font appears on the phone that displays the @3x picture.

So the point here is to distinguish between the screen display of the mobile phone is the @2x type or the @3x type.

CGFloat scale = [UIScreen Mainscreen].scale, it's up. The UIScreen's Scale property is 2 on IPhone 5,6,6s,7,8 and 3 for plus,iphone x printing. So there's the following macro definition

/* FONT-related */

#define Kscreenscale [UIScreen mainscreen].scale//iphone 3GS for 1;4,5,5s,6,7,8 etc for 2;plus x for 3

@3x screen font is 1.5 times times larger than the @2x font

#define KFONTAUTO (size) [Uifont systemfontofsize: (Size * kscreenscale/2.0)]

iOS determines whether the screen displays @2x or @3x to call the font size