希望这能对你有所帮助,
var bottomImage = UIImage(named: "bottom.png")
var topImage = UIImage(named: "top.png")
var size = CGSize(width: 300, height: 300)
UIGraphicsBeginImageContext(size)
let areaSize = CGRect(x: 0, y: 0, width: size.width, height: size.height)
bottomImage!.draw(in: areaSize)
topImage!.draw(in: areaSize, blendMode: .normal, alpha: 0.8)
var newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
祝你一切顺利:)