将“JSON”类型的非可选值与“nil”进行比较总是返回 true。 有什么建议可以解决这个问题吗？

Question

if let vendorId = vendor?.id {
        APIManager.shared.getProducts(vendorId: vendorId, completionHandler: { (json) in

            if json != nil { <<<<<<<<<Comparing non-optional value of type 'JSON' to 'nil' always returns true
                self.products = []
                if let tempProducts = json["products"].array {

                    for item in tempProducts {
                        let product = Product(json: item)
                        self.products.append(product)
                    }

                    self.tableView.reloadData()
                    Helpers.hideActivityIndicator(self.activityIndicator)
                }
            }
        })
    }
}

---

In My APIManager.swift

import Foundation
import Alamofire
import SwiftyJSON
import FBSDKLoginKit

class APIManager {

static let shared = APIManager()

let baseURL = NSURL(string: BASE_URL)

var accessToken = ""
var refreshToken = ""
var expired = Date()

// Request Server Function

func requestServer(method: Alamofire.HTTPMethod , path: String, params: [String: AnyObject]?, encoding: ParameterEncoding, completionHandler: @escaping (JSON?) -> Void ) {

    let url = baseURL?.appendingPathComponent(path)

    refreshTokenIfNeed {
        AF.request(url!, method: method, parameters: params, encoding: encoding, headers: nil).responseJSON{ response in

            switch response.result {
            case .success(let value):
                let jsonData = JSON(value)
                completionHandler(jsonData)
                break

            case .failure:
                completionHandler(nil)
                break
            }
        }
    }

}

// API - Getting the latest order (Customer)

 func getLatestOrder(completionHandler: @escaping (JSON) -> Void) {

    let path = "api/customer/order/latest/"
    let params: [String: Any] = [
        "access_token": self.accessToken
    ]
    requestServer(method: .get, path: path, params: params as [String : AnyObject], encoding: URLEncoding()) { (json) in
        print(json!)
    }
}
}

Answer 1

as json is non optional in your case, comparing it with nil will always return true. You simply cannot compare it with nil. If you expect it to be nil , then it should be optional. If you are sure that it will never be nil , let it be like it is now, just remove the if condition. But be aware that if it goes nil during runtime it would cause crash.