主控制器的关键代码：

ViewController.m

#import "ViewController.h"#import "UIImage+ZR.h"@interface ViewController ()@property (weak, nonatomic) IBOutlet UIImageView *iconV;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];        UIImage *newImage = [UIImage circleImage:@"me" borderWith:3 borderColor:[UIColor greenColor]];    self.iconV.image = newImage;    }@end

 

创建UIImage分类文件：

UIImage+ZR.h

#import 
     
      @interface UIImage (ZR)+(instancetype)circleImage:(NSString *)name borderWith:(CGFloat)borderWith borderColor:(UIColor *)borderColor;@end
     

UIImage+ZR.m

#import "UIImage+ZR.h"@implementation UIImage (ZR)+(instancetype)circleImage:(NSString *)name borderWith:(CGFloat)borderWith borderColor:(UIColor *)borderColor{        UIImage *oldImage = [UIImage imageNamed:name];    //2.开启上下文    CGFloat imageW = oldImage.size.width + 2*borderWith;    CGFloat imageH = oldImage.size.height + 2*borderWith;    CGSize imageSize = CGSizeMake(imageH, imageW);        UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);        //3.取得当前上下文    CGContextRef ctx = UIGraphicsGetCurrentContext();    //4.画圆边框（大圆）    [borderColor set];    CGFloat bigRadius = imageW * 0.5;//半径    CGFloat centerX = bigRadius;//圆心    CGFloat centerY = bigRadius;    CGContextAddArc(ctx, centerX, centerY, bigRadius, 0, M_PI * 2, 0);    CGContextFillPath(ctx);//画圆        //5.小圆    CGFloat smallRadius = bigRadius - borderWith;    CGContextAddArc(ctx, centerX, centerY, smallRadius, 0, M_PI *2, 0);    //裁剪(后面画的东西才会受影响)    CGContextClip(ctx);    //6.画图    [oldImage drawInRect:CGRectMake(borderWith, borderWith, oldImage.size.width, oldImage.size.height)];        //7.取图    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();    //8.结束上下文    UIGraphicsEndImageContext();        return newImage;}@end