UIImageView * vv = [[UIImageView alloc] initWithFrame:CGRectMake(50, 500, 250, 250)];

    vv.image = [UIImage imageNamed:@"logo"];

    CAShapeLayer * maskLayer = [[CAShapeLayer alloc] init];

    maskLayer.frame = vv.bounds;

    maskLayer.path = [UIBezierPath bezierPathWithRoundedRect:vv.bounds cornerRadius:20].CGPath;

    vv.layer.mask = maskLayer;

    [self.view addSubview:vv];