ios,制作阴影

 UIView *r = [[UIView alloc] initWithFrame:CGRectMake(100, 200, 60, 60)];

    r.backgroundColor = [UIColor redColor];

    [self.view addSubview:r];

    r.layer.shadowOffset = CGSizeMake(2, -4);

    r.layer.shadowColor = [UIColor blackColor].CGColor;

    r.layer.shadowOpacity = 0.6;

一,边框偏移量

二,边框颜色

三,边框透明度