xcode エラーが消えない（お菓子検索）

if let items = json.item のInitializer for conditional binding must have Optional type, not '[ViewController.ItemJson]'がエラーが出て消えません。

//
// ViewController.swift
// myokashi
//
// Created by MacOS on 2018/10/15.
// Copyright © 2018年 Swift-Beginners. All rights reserved.
//

import UIKit

class ViewController: UIViewController,UISearchBarDelegate {

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    searchText.delegate = self
    searchText.placeholder = "お菓子の名前を入力して下さい"
    
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBOutlet weak var searchText: UISearchBar!

@IBOutlet weak var tableView: UITableView!

var okashiList : [(maker:String , name:String , link:URL , image:URL)] = []
func searchBarSearchButtonClicked(_ searchBar: UISearchBar){
    view.endEditing(true)
    if let searchWord = searchBar.text{
        print(searchWord)
        searchOkashi(keyWord: searchWord)
    }
}
struct ItemJson: Codable{
    let name: String?
    let maker: String?
    let url: URL?
}
struct ResultJson: Codable{
    let item:[ItemJson]
}

func searchOkashi(keyWord : String) {
    guard let keyword_encode = keyWord.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed) else {
        return
    }
    guard let req_url = URL(string: "http://www.sysbird.jp/toriko/api/?apikey=guest&format=json&keyword=(keyword_encode)&max=10&order=r")else{return}
    print(req_url)
    let req = URLRequest(url: req_url)
    let session = URLSession(configuration: .default, delegate: nil, delegateQueue: OperationQueue.main)
    let task = session.dataTask(with: req, completionHandler: {
        (data, response, error) in
        session.finishTasksAndInvalidate()
        do {
            let decoder = JSONDecoder()
            let json = try decoder.decode(ResultJson.self, from: data!)
            
            **if let items = json.item {**
                for item in items {
                    if let maker = item.maker , let name = item.name , let link = item.url , let image = item.image {
                        let okashi = (maker,name,link,image)
                        self.okashiList.append(okashi)
                    }
                }
                if let okashidbg = self.okashiList.first {
                    print("-------------")
                    print("okashiList[0] = (okashidbg)")
                }
            }
        } catch {
            print("エラーが出ました")
        }
    })
    task.resume()
}