代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
    self.title=@"圆角矩形";
    
    
    UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(50, 100, 100, 100)];
    imageView.backgroundColor=[UIColor redColor];
    //设计其圆角半径
    [imageView.layer setCornerRadius:18.0f];
    [imageView.layer setMasksToBounds:YES];
    [self.view addSubview:imageView];
}