ios - swift管理SQLite数据库，请大神帮忙看看为何总报错“fatal error: Index out of range”。

Question

用swift写了一个程序，添加了一个学生成绩管理的sqlite数据库。用的是XCODE7.3.1。
但是总会在labelId.text = "(arrStu[n].id)"处报错“fatal error: Index out of range”。
请大神们帮忙看看代码

import UIKit

class ViewController: UIViewController {
    //数据库结构：主索引  姓名  语文成绩  数学成绩
    struct stu {
        var id:Int32
        var name:String
        var chinese:Int32
        var math:Int32
        init(id:Int32,name:String,chinese:Int32,math:Int32) {
            self.id = id
            self.name = name
            self.chinese = chinese
            self.math = math
        }
    }
    
    /*定义变量*/
    var arrStu:Array<stu> = []//存储数据库的数组
    var db:COpaquePointer = nil
    var statement:COpaquePointer = nil
    var sql:NSString = ""//SQL指令
    var currentStu = 0//当前数据
    
    @IBOutlet var labelId: UILabel!//显示数据编号
    @IBOutlet var textName: UITextField!//输入姓名
    @IBOutlet var textChinese: UITextField!//输入语文成绩
    @IBOutlet var textMath: UITextField!//输入数学成绩
    @IBOutlet var tableViewSqlite: UITableView!
    @IBOutlet var buttonInsert: UIButton!
    @IBOutlet var buttonWrite: UIButton!

    /*表格的设置*/
    func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return 1
    }
    
    func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int{
        return arrStu.count
    }
    
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{
        let cell : UITableViewCell = tableView.dequeueReusableCellWithIdentifier("cell",forIndexPath: indexPath) as UITableViewCell
        cell.textLabel?.text = "  姓名：\(arrStu[indexPath.row].name)"
        cell.detailTextLabel?.text = "  编号：\(arrStu[indexPath.row].id)  语文：\(arrStu[indexPath.row].chinese)  数学：\(arrStu[indexPath.row].math)"
        return cell
    }
    
    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath){
        buttonToggle(true, writeAble: false)
        currentStu = indexPath.row
        showSingle(currentStu)
    }
    
    /*定义对话框*/
    func alertView(alertView:UIAlertView,clickedButtonAtIndex buttonIndex:Int) {
        if alertView.title == "  更新  " {
            switch (buttonIndex) {
            case 0://单击“确定”按钮的处理
                //确定更新数据，更新数据库
                let sqltem1:String = "UPDATE class101 SET s_name ='" + textName.text! + "',s_math=" + textChinese.text!
                let sqltem2:String = ",s_math=" + textMath.text! + "WHERE s_id=" + labelId.text!
                sql = sqltem1 + sqltem2
                statement = nil
                sqlite3_prepare_v2(db, sql.UTF8String, -1, &statement, nil)
                if sqlite3_step(statement) == SQLITE_DONE {
                    alertMsg("  成功  ", msgStr: "  数据库更新成功！ ")
                } else {
                    alertMsg("  失败  ", msgStr: "  数据库更新失败！ ")
                }
                //更新数组
                arrStu[currentStu].name = textName.text!
                arrStu[currentStu].chinese = Int32(Int(textChinese.text!)!)
                arrStu[currentStu].math = Int32(Int(textMath.text!)!)
                tableViewSqlite.reloadData()
            default:
                break
            }
        } else if alertView.title == "  删除  " {
            switch (buttonIndex) {
            case 0://单击“确定”按钮的处理
                //确定删除数据，更新数据库
                sql = "DELETE FROM class101 WHERE s_id=" + labelId.text!
                statement = nil
                sqlite3_prepare_v2(db, sql.UTF8String, -1, &statement, nil)
                if sqlite3_step(statement) == SQLITE_DONE {
                    alertMsg("  成功  ", msgStr: "  数据库删除成功！ ")
                } else {
                    alertMsg("  失败  ", msgStr: "  数据库删除失败！ ")
                }
                arrStu.removeAtIndex(currentStu)
                tableViewSqlite.reloadData()
                //数据删除后，显示下一笔
                if currentStu == arrStu.count {
                    currentStu -= 1
                }
                showSingle(currentStu)
            default:
                break
            }
        }
    }
    
    /*创建自定义函数*/
    func showSingle(n:Int) {//显示单笔数据
        labelId.text = "\(arrStu[n].id)"
        textName.text = arrStu[n].name
        textChinese.text = "\(arrStu[n].chinese)"
        textMath.text = "\(arrStu[n].math)"
    }
    
    func buttonToggle(insertAble:Bool,writeAble:Bool) -> Void {
        buttonInsert.enabled = insertAble
        buttonWrite.enabled = writeAble
    }
    
    func alertMsg(titleStr:String,msgStr:String) -> Void {
        let alertView:UIAlertView = UIAlertView(title:titleStr,message: msgStr,delegate: self,cancelButtonTitle: "  确定  ")
        alertView.show()
    }
    
    /*页面载入时*/
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        buttonToggle(true, writeAble: false)
        //第一次执行时将数据库复制到Documents文件夹
        let fm:NSFileManager = NSFileManager()
        db = nil
        let src:String = NSBundle.mainBundle().pathForResource("student", ofType: "sqlite")!
        let dst:String = NSHomeDirectory() + "/Documents/student.sqlite"
        if !fm.fileExistsAtPath(dst) {
            try! fm.copyItemAtPath(src, toPath: dst)
        }
        //连接及打开数据库
        if sqlite3_open(dst, &db) != SQLITE_OK {
            alertMsg("  失败  ", msgStr: "  无法打开数据库！ ")
        }
        //逐笔读取数据行
        while sqlite3_step(statement) == SQLITE_ROW {
            let id = sqlite3_column_int(statement, 0)
            let temName = sqlite3_column_text(statement, 1)
            let name = String.fromCString(UnsafePointer<CChar>(temName))
            let chinese = sqlite3_column_int(statement, 2)
            let math = sqlite3_column_int(statement, 3)
            let student:stu = stu(id: id, name: name!, chinese: chinese, math: math)
            arrStu.append(student)//将数据行存入数组
        }
        sqlite3_finalize(statement)
        tableViewSqlite.reloadData()
        showSingle(0)//开始时显示第一笔数据
    }

    /*按键的触发事件*/
    @IBAction func modifyClick(sender: UIButton) {//修改
        let alertModify:UIAlertView = UIAlertView()
        alertModify.title = "  更新  "
        alertModify.message = "  确定要更新数据吗?  "
        alertModify.delegate = self
        alertModify.addButtonWithTitle("  确定  ")
        alertModify.addButtonWithTitle("  取消  ")
        alertModify.show()
    }//更新数据
    
    @IBAction func deleteClick(sender: UIButton) {//删除
        if arrStu.count > 1 {//数据大于1笔才允许删除
            let alertDelete:UIAlertView = UIAlertView()
            alertDelete.title = "  删除  "
            alertDelete.message = "  确定要删除数据吗?  "
            alertDelete.delegate = self
            alertDelete.addButtonWithTitle("  确定  ")
            alertDelete.addButtonWithTitle("  取消  ")
            alertDelete.show()
        } else {
            self.alertMsg("  失败  ", msgStr: "  只有一笔数据时不可删除！ ")
        }
    }
    
    @IBAction func insertClick(sender: UIButton) {//新增
        buttonToggle(false, writeAble: true)
        labelId.text = ""
        textName.text = ""
        textChinese.text = ""
        textMath.text = ""
    }
    
    @IBAction func writeClick(sender: UIButton) {//写入
        buttonToggle(true, writeAble: false)
        sql = "INSERT INTO class101 (s_name, s_chinese, s_math) VALUES ('" + textName.text! + "'," + textChinese.text! + "," + textMath.text! + ");"
        statement = nil
        sqlite3_prepare_v2(db, sql.UTF8String, -1, &statement, nil)
        if sqlite3_step(statement) == SQLITE_DONE {
            alertMsg("  成功  ",msgStr:"  数据库新增成功！ ")
        } else {
            alertMsg("  失败  ",msgStr:"  数据库新增失败！ ")
        }
        let id = Int32(sqlite3_last_insert_rowid(db))
        let name = textName.text
        let chinese = Int32(Int(textChinese.text!)!)
        let math = Int32(Int(textMath.text!)!)
        let student:stu = stu(id:id, name:name!, chinese:chinese, math:math)
        arrStu.append(student)//将数据行存入数组
        tableViewSqlite.reloadData()
        showSingle(arrStu.count - 1)
        currentStu = arrStu.count - 1
    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
}

Answer 1

Selesai! ! !
Saya cuba menambah sekeping kod semasa halaman dimuatkan, supaya paparan jadual akan memaparkan pangkalan data sedia ada dalam pangkalan data semasa memuatkan, supaya tiada ralat akan dilaporkan. Besar kemungkinan jadual kod asal tidak memaparkan data semasa memuatkan, jadi tiada data dalam jadual, jadi fungsi seterusnya akan melaporkan ralat "ralat maut: Indeks di luar julat".

 /*Apabila halaman dimuatkan*/
    mengatasi fungsi viewDidLoad() {
        super.viewDidLoad()
        // Lakukan sebarang persediaan tambahan selepas memuatkan paparan, lazimnya dari mata pena.
        buttonToggle(true, writeAble: false)
        //Salin pangkalan data ke folder Dokumen apabila melaksanakan buat kali pertama
        biarkan fm:NSFileManager = NSFileManager()
        db = tiada
        biarkan src:String = NSBundle.mainBundle().pathForResource("pelajar", ofType: "sqlite"!
        biarkan dst:String = NSHomeDirectory() + "/Documents/student.sqlite"
        jika !fm.fileExistsAtPath(dst) {
            cuba! fm.copyItemAtPath(src, toPath: dst)
        }
        //Sambung dan buka pangkalan data
        jika sqlite3_open(dst, &db) != SQLITE_OK {
            alertMsg("Gagal", msgStr: "Tidak dapat membuka pangkalan data!")
        }
        let sql:NSString = "SELECT * FROM class101"
        jika sqlite3_prepare_v2(db,sql.UTF8String,-1,&statement,nil) != SQLITE_OK {
            let alertView:UIAlertView = UIAlertView(title:" Failed to read ",message: " Failed to read the database! ",delegate: self,cancelButtonTitle: " OK ")
            alertView.show()
            keluar(1)
        }
        arrStu.removeAll(keepCapacity: true)
        //Baca baris data satu demi satu
        manakala sqlite3_step(penyataan) == SQLITE_ROW {
            biarkan id = sqlite3_column_int(penyataan, 0)
            biarkan temName = sqlite3_column_text(penyataan, 1)
            biarkan nama = String.fromCString(UnsafePointer<CChar>(temName))
            biarkan cina = sqlite3_column_int(penyataan, 2)
            biarkan matematik = sqlite3_column_int(penyataan, 3)
            biarkan pelajar:stu = stu(id: id, nama: nama!, cina: cina, matematik: matematik)
            arrStu.append(pelajar)//Simpan baris data ke dalam tatasusunan
        }
        sqlite3_finalize(statement)
        tableViewSqlite.reloadData()
        showSingle(0)//Paparkan data pertama pada permulaan
    }

Sesiapa sahaja yang berminat boleh membantu saya melihat di mana saya perlu menambah baik Apabila keseluruhan kod berjalan, mengklik pada titik pengubahsuaian akan muncul kotak dialog yang tidak berjaya.

Answer 2

Berdasarkan gesaan, ralat sepatutnya adalah bahawa subskrip keluar dari had semasa mengakses arrStu Bolehkah anda menyemak panjang arrStu? Juga, jika tidak, mengapa ia akan membawa kepada situasi di mana saya perlu mengakses elemen yang tidak wujud dalam tatasusunan?