CALayer中的iOS Swift问题渲染标签

Question

I am trying to render a Label in a CALayer and the background of the layer iconLayer is being placed on top of the Label.

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

    }

Below is what the view looks like with the background.

Below is what the view looks like with the background removed.

It seems the icon is not getting added to the layer iconLayer except it just getting added to the context.

Answer 1

I ended up fixing it with the following code.

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

    }