#import "MainViewController.h"

 @interface MainViewController ()

 @end

 @implementation MainViewController

 - (void)viewDidLoad {

    [super viewDidLoad];

    // Do any additional setup after loading the view.

//    创建圆形头像图标

    UIImageView *avatar=[[[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 300, 300)]autorelease];

//    指定头像。imageNamed:默认图片格式png,其他图片需加后缀(如.jpg),否则检索不到

    avatar.center=self.view.center;

    avatar.image=[UIImage imageNamed:@"imge2.jpg"];

    avatar.backgroundColor=[UIColor blackColor];

//    使用CAShapeLayer将视图改为圆形

    CAShapeLayer *shapeLayer=[CAShapeLayer layer];

//    设置形状路径(使用贝塞尔曲线)

    UIBezierPath *circlePath=[UIBezierPath bezierPathWithArcCenter:CGPointMake(150, 150) radius:120 startAngle:0 endAngle:M_PI*2 clockwise:YES];

//    为形状图层指定路径

    shapeLayer.path=circlePath.CGPath;

//    为当前视图的图层添加圆形遮罩图层

    avatar.layer.mask=shapeLayer;

    [self.view addSubview:avatar];//avatar:用户头像

 }