React Native Swift 转义闭包

Question

我正在尝试使用 Swift 为 IOS 在 React native 中实现本机模块。

我有一个函数 getRandomFoodWithCompletionHandler() 我试图从 API 获取一些东西，然后使用 promises 通过桥将它发送回 JS。我使用 resolve:RCTPromiseResolveBlock 函数，但是当我使用它时出现错误 转义闭包捕获非转义参数'resolve'


struct Food: Identifiable, Decodable {
      var id: Int
      var uid: String
      var dish: String
      var description: String
      var ingredient: String
      var measurement: String
  }

  @objc
  func getRandomFoodWithCompletionHandler(_ resolve:RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) {
      guard let url = URL(string: "https://random-data-api.com/api/food/random_food") else { fatalError("Missing URL") }

      let urlRequest = URLRequest(url: url)

      let dataTask = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
          if let error = error {
              print("Request error: ", error)
        
              return
          }

          guard (response as? HTTPURLResponse)?.statusCode == 200 else { return }
          guard let data = data else { return }
          do {
               let decodedFood = try JSONDecoder().decode(Food.self, from: data)
               print("Completion handler decodedFood", decodedFood)
               
               resolve(decodedFood)
            
           } catch {
               print("Error decoding", error)
           }
      }

      dataTask.resume()
  }

Answer 1

使您的 resolve: RCTPromiseResolveBlock 参数成为转义块：

func getRandomFoodWithCompletionHandler(
    _ resolve: @escaping RCTPromiseResolveBlock,
    reject: @escaping RCTPromiseRejectBlock
) {

“转义”块本质上是一个即使在原始函数已经完成执行时也可以调用的块，例如当它是异步完成处理程序时。在Swift中因为内存的关系需要区分这种情况allocations/deallocations.

React Native Swift 转义闭包

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swift

react-native