Alpha Map在SceneKit Swift iOS中不起作用

Question

I have tray to apply diffuse, metalness, normal, roughness and Alpha map on model but all map are working but only alpha map is not working. How to make transparent glass in scenekit? i have tray to below code in swift iOS. Can anyone tell me specific reason for this?.

if let finishMap = finish.finishMap {
      if let diffuseTexturePath = finishMap.diffuseMapUrl {
            disPatchGroup.enter()
            self.dataProvider.fetchTextureFile(forpath: diffuseTexturePath, successBlock: { (success, imageObject) in
                material.diffuse.contents = imageObject
                disPatchGroup.leave()
            }, failureBlock: { (error) in
                disPatchGroup.leave()
            })
        }

       if let metalTexturePath = finishMap.metalnessMapUrl {
            disPatchGroup.enter()
            self.dataProvider.fetchTextureFile(forpath: metalTexturePath, successBlock: { (success, imageObject) in
                material.metalness.contents = imageObject
                disPatchGroup.leave()
            }, failureBlock: { (error) in
                disPatchGroup.leave()
            })
        }

        if let roughnessTexturePath = finishMap.roughnessMapUrl {
            disPatchGroup.enter()
            self.dataProvider.fetchTextureFile(forpath: roughnessTexturePath, successBlock: { (success, imageObject) in
               material.roughness.contents = imageObject
                disPatchGroup.leave()
            }, failureBlock: { (error) in
                disPatchGroup.leave()
            })
        }

        if let normalTexturePath = finishMap.normalMapUrl {
            disPatchGroup.enter()
            self.dataProvider.fetchTextureFile(forpath: normalTexturePath, successBlock: { (success, imageObject) in
                material.normal.contents = imageObject
                disPatchGroup.leave()
            }, failureBlock: { (error) in
                disPatchGroup.leave()
            })
        }
        if let transparentTexturePath = finishMap.transparentMapUrl {
            disPatchGroup.enter()
            self.dataProvider.fetchTextureFile(forpath: transparentTexturePath, successBlock: { (success, imageObject) in

               material.transparent.contents = imageObject

                disPatchGroup.leave()
            }, failureBlock: { (error) in
                disPatchGroup.leave()
            })
        }

        }

Answer 1

set your transparency map to rbgZero. there are a few transparency modes, the default is by alpha i think (not sure), if you want to use a grayscale image as a map then you need to use rgbZero

material.transparencyMode   = .rgbZero