刚刚无聊，画了一个月亮。
- (void)viewDidLoad {
[super viewDidLoad];
self.view.layer.backgroundColor = [UIColor blackColor].CGColor;
CALayer *layer = [CALayer layer];
//尺寸
layer.bounds = CGRectMake(0, 0, 100, 100);
//中心点
layer.position = CGPointMake(250, 100);
//背景色
layer.backgroundColor = [UIColor blackColor].CGColor;
//设置圆角
layer.cornerRadius = 50.f;
[self.view.layer addSublayer:layer];
//阴影颜色
layer.shadowColor = [UIColor yellowColor].CGColor;
//阴影偏移量
layer.shadowOffset = CGSizeMake(10, 10);
//透明度
layer.shadowOpacity = 1;
}