当我尝试混合两个图像时，表达式类型不明确，没有更多的上下文错误消息

Question

我正在尝试使用以下代码混合两个相同大小的图像，但是 "filteredImage.image？.draw(in： areaSize， blendMode： .normal， alpha： opa(" 此代码将显示错误消息，指出"表达式类型不明确，没有更多上下文"。怎么了？

let originalWidth:CGFloat  = originalImageView.frame.size.width
let originalHeight:CGFloat = originalImageView.frame.size.height
var opa = intensity * 0.01
let size = CGSize(width: originalWidth, height: originalHeight)
UIGraphicsBeginImageContext(size)
let areaSize = CGRect(x: 0, y: 0, width: size.width, height: size.height)
let blendImageSize = areaSize
originalImageView.image?.draw(in: areaSize, blendMode: .normal, alpha: 1.0)
filteredImageView.image?.draw(in: areaSize, blendMode: .normal, alpha: opa)
originalImageView.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

Answer 1

更改

alpha: opa

自

alpha: CGFloat(opa)