Question

我正在使用SQLite Library并且在使用中它说let db = try Connection("path/to/db.sqlite3")我有sqlite数据库位于文档中。但是当我尝试建立连接时会抛出错误call can throw but errors cannot be thrown out of a property initializer

这是我的代码：

import UIKit
import SQLite

class SearchViewController: UIViewController, UITextFieldDelegate {

let db = try Connection("/Users/macbookpro/Documents/db.sqlite") //error
let categoryVC = CategoryViewController()
let UseFullVC = UseFullViewController()
let MapVC = MapViewController()
let EventVC = SearchResultOnlineVC()

@IBOutlet weak var searchTextField: UITextField!

override func viewDidLoad() {
    super.viewDidLoad()

    self.title = "Search"

    searchTextField.delegate = self
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}
}

我也尝试在viewDidLoad中放置连接但仍然无法正常工作

出了什么问题？

Answer 1

由于Connection初始值设定项可以抛出异常，因此需要在do/catch块中调用它。

所以你应该将声明改为：

var db : Connection?

并在ViewDidLoad中初始化：

do{
    self.db = try Connection("/Users/macbookpro/Documents/db.sqlite")
} catch {
    print("Unable to create connection: \(error)")
}

Answer 2

import UIKit
import SQLite

let sharedInstance = DBModelManager()

class DBModelManager: NSObject {
  var database: Connection!

 class func getInstance() -> DBModelManager
 {
     if(sharedInstance.database == nil)
     {
         do{
             let documentDirectory = try FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
             let fileUrl = documentDirectory.appendingPathComponent("dbname").appendingPathExtension("sqlite3")
             sharedInstance.database = try Connection(fileUrl.path)

         }catch{
             print("DB Error \(error)")
         }
     }
     return sharedInstance
  }
}

以这种方式调用数据库实例

try DBModelManager.getInstance().database!.prepare()

无法连接到SQLite数据库Swift 3

2 个答案: