如何在仍显示焦点的同时为tvOS创建具有背景颜色的按钮？

Question

我想要做的就是为所有状态的按钮添加背景颜色.但是我希望在tvOS故事板中使用系统按钮时保持"免费"获得的自动焦点阴影.到目前为止,我还没有找到允许这种情况的组合.

或者,我也有兴趣在按钮聚焦时以编程方式添加阴影的方法,但是没有子按钮(我还没有尝试过),我也不知道该怎么做.

Answer 1

您可以为自定义按钮添加阴影,如下所示:

- (void)didUpdateFocusInContext:(UIFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator
{
    context.nextFocusedView.layer.shadowOffset = CGSizeMake(0, 10);
    context.nextFocusedView.layer.shadowOpacity = 0.6;
    context.nextFocusedView.layer.shadowRadius = 15;
    context.nextFocusedView.layer.shadowColor = [UIColor blackColor].CGColor;
    context.previouslyFocusedView.layer.shadowOpacity = 0;
}

Answer 2

对简单的颜色变化不满意,所以我创建了一个自定义按钮子类,看起来更像是系统按钮带来的默认动画 -

class CustomButton: UIButton
{
    private var initialBackgroundColour: UIColor!


    required init?(coder aDecoder: NSCoder)
    {
        super.init(coder: aDecoder)

        initialBackgroundColour = backgroundColor
    }

    override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator)
    {
        coordinator.addCoordinatedAnimations(
        {
            if self.focused
            {
                self.backgroundColor = UIColor.whiteColor()

                UIView.animateWithDuration(0.2, animations:
                {
                    self.transform = CGAffineTransformMakeScale(1.1, 1.1)
                },
                completion: 
                {
                    finished in

                    UIView.animateWithDuration(0.2, animations:
                    {
                        self.transform = CGAffineTransformIdentity
                    },
                    completion: nil)
                })
            }
            else
            {
                self.backgroundColor = self.initialBackgroundColour
            }
        },
        completion: nil)
    }
}

没有什么太复杂,但完成工作

Answer 3

覆盖didUpdateFocusInContext方法并检查下一个焦点视图是否为按钮,如果是,则自定义其UI,并将其设置回orignal状态检查context.previousFocusedView是该按钮,如下所示

- (void)didUpdateFocusInContext:(UIFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator
{
    if (context.nextFocusedView == _button)
    {
        // set background color
    }
    else if (context.previousFocusedView == _button)
    {
        // set background color to background
    }
}