iOS图片圆角设置
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];