ios - 无法将类型 '__NSCFNumber' (0x25418e000) 的值转换为 'NSString'

Question

在将我的 Mac OS 和 Xcode 从 7 更新到 11.1 并将 Swift 2.2 更新到 Swift 4 后，我在查询 Stored in aWords: String 中收到标题错误:以前代码在 swift 2.2 中运行完美，但现在这个查询给出了一个错误并且没有得到修复。查询访问数据库获取国家和城市名称，然后是纬度和经度。

    func updateSearchResults(for searchController: UISearchController)
    {
        if searchController.searchBar.text == ""
        {
            return
        }
        self.openDatabase()
        filteredResults.removeAllObjects()
        if let wordsResultSet = database.executeQuery(
            "SELECT * FROM citiesTable,country  WHERE country.country_id = 
    citiesTable.country_id and cityName LIKE '\
    (searchController.searchBar.text!)%' LIMIT 50", withArgumentsIn: nil)

        {
            while wordsResultSet.next()
            {
        let aWord: String =  (wordsResultSet["cityName"] as! String) + " , 
" + (wordsResultSet["name"] as! String) +  "-$-" +
            (wordsResultSet["latitude"] as! String) + "-$-" +  
(wordsResultSet["longitude"] as! String)

                filteredResults.add(aWord)
            }
        } else {
            print("select failed: \(String(describing: database.lastErrorMessage()))")
        }

        database.close()
        self.tableVw.reloadData()

    }

代码中的错误信息 swift 2.2 中代码的先前工作输出是:

Answer 1

错误#1

Could not cast value of type '__NSCFNumber' (0x25418e000) to 'NSString'

解决方案:

将纬度和经度转换为Double

---

错误#2

The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions

解决方案:

将字典值赋给变量，然后用 Sting Interpolation 连接字符串

---

let city = wordsResultSet["cityName"] as! String
let name = wordsResultSet["name"] as! String
let latitude = wordsResultSet["latitude"] as! Double
let longitude = wordsResultSet["longitude"] as! Double

let aWord = "\(city) , \(name)-$-\(latitude)-$-\(longitude)"