ios - 从 IOS 应用程序同时多次查询数据库导致崩溃

Question

我正在使用 MySqlDriver 直接从我的 iOS 应用程序访问关系数据库。但如果我同时使用多个查询，则会导致驱动程序崩溃。驱动程序位于以下库中: https://github.com/mcorega/MySqlSwiftNative

我使用的代码是:

class ViewController: UIViewController {

    let con = MySQL.Connection()
    override func viewDidLoad() {
        super.viewDidLoad()
        let db_name = "database"

        do{
            try con.open("localhost", user: "root", passwd: "1234")
            try con.use(db_name)
        }
        catch (let e) {
            print(e)
        }
    }

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


    @IBAction func onClickButton(sender: UIButton!){
        DispatchQueue.global(qos: .background).async {
            print("gone")
            let select_stmt = try? self.con.prepare("query")
                    let stRes = try? select_stmt!.query([])
                    if let rr = try? stRes!.readAllRows() {
                        print(rr)
                        if rr!.count > 0{
            //                completion(true, (rr.first!))
                        }else{
            //                completion(true, [[String: Any]]())
                        }
                    }
        }
    }

}

Answer 1

我已经更新了您的代码。请检查并告诉我它是否适合您。

@IBAction func onClickButton(sender: UIButton!){
    DispatchQueue.main.async {
    print("Success")
        let select_stmt = try? self.con.prepare("query")
        let stRes = try? select_stmt!.query([])
        if let rr = try? stRes!.readAllRows() {
           print(rr)
           if rr!.count > 0{
        //                completion(true, (rr.first!))
                   }else{
        //                completion(true, [[String: Any]]())
                    }
         }
    }
}