Question

我尝试从函数中返回String，但是出现错误“使用未解析的标识符nameOfFlower”。这是我的功能：

func detectFlower(image: CIImage) -> String {
        guard let model = try? VNCoreMLModel(for: FlowerModels().model) else {
            fatalError("Cannot import a model.")
        }

        let request = VNCoreMLRequest(model: model) { (request, error) in

            let classification = request.results?.first as? VNClassificationObservation

            var nameOfFlower = String(classification?.identifier ?? "Unexpected type")



        }

        let handler = VNImageRequestHandler(ciImage: image)

        do {
            try handler.perform([request])
        } catch {
            print(error)
        }

        return nameOfFlower
       }

代码有什么问题？

Answer 1

它的异步代码..所以使用闭包作为完成块

func detectFlower(image: CIImage,completion: @escaping (_ getString:String?,_ error:Error?)-> Void)  {
     guard let model = try? VNCoreMLModel(for: FlowerModels().model) else {

         fatalError("Cannot import a model.")
     }

     let request = VNCoreMLRequest(model: model) { (request, error) in

         let classification = request.results?.first as? VNClassificationObservation

         var nameOfFlower = String(classification?.identifier ?? "Unexpected type")

         completion(nameOfFlower,nil)

     }

     let handler = VNImageRequestHandler(ciImage: image)

     do {
         try handler.perform([request])
     } catch {
         print(error)
           completion(nil,error)
     }


    }

使用方法

     detectFlower(image: yourImage) { (flowerString, error) in
                // you get optional flower string here
            }

无法从函数返回字符串

1 个答案: