仅在下面的一个视图上绘制阴影

Question

我有一个带有阴影的UIView。我希望在下面的单个视图上仅绘制阴影。问题是，下面的视图范围更小。

当前结果：

想要的结果：

注意：

用户通过拖入或拖出蓝色视图来动态更新屏幕。因此，解决方案不能是静态的。

有什么办法可以做到吗？

Answer 1

试试这个：

1. 灰色视图：设置 cliptobounds = true
2. 蓝色视图不应该是灰色视图的子视图，并且没有阴影。
3. 在灰色视图中创建一个子视图，它看起来与蓝色视图完全相同，为此子视图设置阴影。

Answer 2

1. 创建支架视图。
2. 创建两个形状：蓝色框和灰色框。
3. 将用于两个框的路径组合起来，创建第三个形状，用于遮盖支架视图。

UIView * background = [UIView new];
background.frame = self.view.bounds;
background.backgroundColor = [self colourForHex:@"#F5F5F5" andAlpha:1.0f];
[self.view addSubview:background];

UIView * holder = [UIView new];
holder.frame = CGRectMake((w-300)/2, (h-300)/2, 300, 300);
[background addSubview:holder];

UIBezierPath * boxPath = [UIBezierPath bezierPath];
[boxPath moveToPoint:CGPointMake(0, 0)];
[boxPath addLineToPoint:CGPointMake(0, 100)];
[boxPath addLineToPoint:CGPointMake(200, 100)];
[boxPath addLineToPoint:CGPointMake(200, 0)];
[boxPath closePath];

UIBezierPath * castPath = [UIBezierPath bezierPath];
[castPath moveToPoint:CGPointMake(10, 100)];
[castPath addLineToPoint:CGPointMake(0, 200)];
[castPath addLineToPoint:CGPointMake(200, 200)];
[castPath addLineToPoint:CGPointMake(190, 100)];
[castPath closePath];

CAShapeLayer * boxShape = [CAShapeLayer layer];
boxShape.path = boxPath.CGPath;
boxShape.fillColor = [self colourForHex:@"#1A0F53" andAlpha:1.0f].CGColor;
boxShape.shadowColor = [UIColor blackColor].CGColor;
boxShape.shadowOffset = CGSizeMake(5, 5);
boxShape.shadowRadius = 2.0f;
boxShape.shadowOpacity = 0.5f;
[holder.layer addSublayer:boxShape];

CAShapeLayer * castShape = [CAShapeLayer layer];
castShape.path = castPath.CGPath;
castShape.fillColor = [self colourForHex:@"#D8D8D8" andAlpha:1.0f].CGColor;
[holder.layer insertSublayer:castShape below:boxShape];

UIBezierPath * maskPath = [UIBezierPath bezierPath];
[maskPath appendPath:boxPath];
[maskPath appendPath:castPath];

CAShapeLayer * maskShape = [CAShapeLayer layer];
maskShape.path = maskPath.CGPath;
[holder.layer setMask:maskShape];

根据评论编辑：要添加 gif 中显示的动画，您可以将 UIPanGestureRecogniser 添加到视图并在用户滑动时偏移（原始要求），或者，在上面，我添加了一些类似这样的代码：

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{

[UIView animateWithDuration:0.5f
                      delay:0.0f
                    options:UIViewAnimationOptionCurveEaseInOut
                 animations:^{
                     boxShape.transform = CATransform3DMakeTranslation(100, 0, 0);
                 }
                 completion:^(BOOL finished){
                 }];
            });