Two ways iOS adds rounded corners to uiimage

As we all know, adding rounded corners to the picture is a calayer Cornerradius,

Like what:

The most straightforward approach:

imgview.layer.cornerradius1=110;imgview.clipstobounds = YES;this thing off-screen rendering (off-screen-rendering), is very expensive performance; There are a lot of companies that interview will ask, how do you set the picture rounded, if youonly answer this method, then unfortunately, no bonus points. Here's a better way to do this:#import "Bys.h"

@implementation Bys

-(uiimage*) Imagewithcornerradius: (cgfloat) radius{

CGRect rect = (cgrect) {0.f,0.f,self.size};

void Uigraphicsbeginimagecontextwithoptions (cgsize size, BOOL opaque, cgfloat scale);
size--with Uigraphicsbeginimagecontext, parameter size for newly created bitmap contexts
opaque-Transparent switch, if the graphic is not transparent at all, set to Yes to optimize the storage of the bitmap.
scale-– Scaling Factor
Uigraphicsbeginimagecontextwithoptions (Self.size, NO, [UIScreen Mainscreen].scale);

Draw a curve with rounded corners based on a rectangle
Cgcontextaddpath (Uigraphicsgetcurrentcontext (), [Uibezierpath Bezierpathwithroundedrect:rect CornerRadius:radius] . Cgpath);

[Self drawinrect:rect];

Picture scaling, non-thread safe
UIImage * image = Uigraphicsgetimagefromcurrentimagecontext ();

Close context
Uigraphicsendimagecontext ();

return image;
}

add an extension API to UIImage to create rounded pictures: This is on-screen-rendering

Two ways iOS adds rounded corners to uiimage