Swift中实现便捷的异步操作

1. 定义操作符：

//
//  AsyncTask.swift
// 
//  Created by lenbo lan on 2021/2/5.
//

typealias Action = () -> Void
typealias AsyncTask = (_ act: @escaping Action) -> Void

// 定义优先级
precedencegroup AsyncOperater {
    associativity: left
    higherThan: AssignmentPrecedence
}

// 定义操作符
infix operator +>: AsyncOperater

func +>(left:@escaping AsyncTask, right:@escaping AsyncTask) -> AsyncTask {
    return { complete in
        left {
            right {
                complete()
            }
        }
    }
}

2. 使用：

       func uploadProfileImage(complete: @escaping Action) {
            AF.upload(multipartFormData: { multipartFormData in
                multipartFormData.append(uploadData, withName: "imgUploader", fileName: "\(filename).jpg", mimeType: "image/jpeg")
            }, to: server_api.upload)
            .uploadProgress { progress in
                print(CGFloat(progress.fractionCompleted)*100)
            }
            .responseJSON { response in
                debugPrint(response)
                switch response.result {
                case .success(let value):
                    let dict = JSON(value)
                    let imageUrl = dict["image"].stringValue
                    print("image url: \(imageUrl)")
                    UserDefaultsManager.shared.profileImageUrl = imageUrl
                
                    // 回调
                    complete()
                case .failure:
                    print("upload image failure")
                    return
                }
            }
        }
        
        func regist(complete: @escaping Action) {
            let parameters = ["name": fullName,
                              "username": username,
                              "email": email,
                              "profileImageUrl": profileImageUrl,
                              "password": password]
            AF.request(server_api.regist, method: .post, parameters: parameters)
                .responseJSON { response in
                    print("Response JSON: \(response.value ?? "")")
                    
                    // 回调
                    complete()
                }
        }
        
        // 执行操作
        let taskRegist = uploadProfileImage +> regist

        taskRegist {
            DispatchQueue.main.async {
                print("sign up complete")
            }
        }

3. 参考于：

http://www.voidcn.com/article/p-fcxrweyk-ym.html

https://docs.swift.org/swift-book/ReferenceManual/Declarations.html

https://developer.apple.com/documentation/swift/swift_standard_library/operator_declarations