iOS Swift 在 CALayer 中渲染标签的问题

Question

我正在尝试在 CALayer 中渲染标签，并且图层 iconLayer 的背景被放置在标签的顶部。

func textToImage(drawText: NSString, inImage: UIImage, atPoint:CGPoint)->UIImage{
        let textColor: UIColor = UIColor(red: 85/255, green: 150/255, blue: 230/255, alpha: 1)
        let textFont: UIFont = UIFont(name: "WeatherIcons-Regular", size: 20)!

        UIGraphicsBeginImageContext(inImage.size)

        let layer = CALayer()
        let iconLayer = CALayer()

        layer.frame = CGRectMake(0, 0, inImage.size.width, inImage.size.height)

        inImage.drawInRect(CGRectMake(0, 0, inImage.size.width, inImage.size.height))

        let imageSubLayer = CALayer()
        imageSubLayer.contents = inImage.CGImage

        let rect: CGRect = CGRectMake(atPoint.x, atPoint.y, 30, 30)

        iconLayer.frame = rect
        iconLayer.cornerRadius = 15.0
        iconLayer.backgroundColor = UIColor.whiteColor().CGColor
        layer.renderInContext(UIGraphicsGetCurrentContext()!)

        iconLayer.borderColor = textColor.CGColor
        iconLayer.borderWidth = 1


        let label = UILabel(frame: CGRect(x: 0, y: 0, width: 30, height: 30))
        label.text = drawText as String
        label.font = textFont
        label.textColor = textColor
        label.layer.renderInContext(UIGraphicsGetCurrentContext()!)
        iconLayer.contents = label


        layer.addSublayer(iconLayer)
        layer.addSublayer(imageSubLayer)

        layer.renderInContext(UIGraphicsGetCurrentContext()!)


        let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()

        UIGraphicsEndImageContext()

        return newImage

    }

下面是带有背景的 View 的样子。

下面是删除背景后的 View 。

图标似乎没有添加到图层 iconLayer 中，只是添加到了上下文中。

Answer 1

我最终用以下代码修复了它。

func textToImage(drawText: NSString, inImage: UIImage, atPoint:CGPoint)->UIImage{
        let textColor: UIColor = UIColor(red: 85/255, green: 150/255, blue: 230/255, alpha: 1)
        let textFont: UIFont = UIFont(name: "WeatherIcons-Regular", size: 20)!

        UIGraphicsBeginImageContext(inImage.size)

        let layer = CALayer()
        let iconLayer = CALayer()

        layer.frame = CGRectMake(0, 0, inImage.size.width, inImage.size.height)

        inImage.drawInRect(CGRectMake(0, 0, inImage.size.width, inImage.size.height))

        let imageSubLayer = CALayer()
        imageSubLayer.contents = inImage.CGImage

        let rect: CGRect = CGRectMake(atPoint.x, atPoint.y, 30, 30)

        iconLayer.frame = rect
        iconLayer.cornerRadius = 15.0
        iconLayer.backgroundColor = UIColor.whiteColor().CGColor
        layer.renderInContext(UIGraphicsGetCurrentContext()!)

        iconLayer.borderColor = textColor.CGColor
        iconLayer.borderWidth = 1


        let label = UILabel(frame: CGRect(x: 0, y: 0, width: 30, height: 30))
        label.text = drawText as String
        label.font = textFont
        label.textColor = textColor
        iconLayer.contents = label.layer


        layer.addSublayer(iconLayer)
        layer.addSublayer(label.layer)
        layer.addSublayer(imageSubLayer)

        layer.renderInContext(UIGraphicsGetCurrentContext()!)


        let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()

        UIGraphicsEndImageContext()

        return newImage

    }