快速保存sqlite数据库 [英] Saving sqlite database with swift

问题描述

完成本教程后

http://www.techotopia.com/index.php/An_Example_SQLite_based_iOS_8_Application_using_Swift_and_FMDB

我发现数据库仅在应用程序运行时创建.第二次运行应用程序时，我该如何访问数据库.我的最终目标是创建一个数据库并使用数据来显示事物.

I found that the database was only created while the app was running. How could I access the database the second time I run the app. And my final goal is to create a database and use the data to display things.

推荐答案

我使用以下简单包装程序:

I use the following simple wrapper:

private let _SingletonSharedInstance = SQLite()

class SQLite {

  private var db: COpaquePointer = nil
  private let path = "<path to your db>.rdb"
  private var statement: COpaquePointer = nil
  private let SQLITE_STATIC = sqlite3_destructor_type(COpaquePointer(bitPattern: 0))      // http://stackoverflow.com/a/26884081/1271826
  private let SQLITE_TRANSIENT = sqlite3_destructor_type(COpaquePointer(bitPattern: -1))

  class var sharedInstance : SQLite {
    return _SingletonSharedInstance
  }

  init() {
    if sqlite3_open(path, &db) != SQLITE_OK {
      fatalError("database not found")
    }
  }

  func select(query:String) -> Bool {
    if sqlite3_prepare_v2(db, "SELECT \(query)", -1, &statement, nil) == SQLITE_OK { return true }
    let errmsg = String.fromCString(sqlite3_errmsg(db))
    println("error preparing select: \(errmsg!)")
    return false
  }

  func prepare(query:String) -> Bool {
    if sqlite3_prepare_v2(db, query, -1, &statement, nil) == SQLITE_OK { return true }// "insert into test (name) values (?)"
    let errmsg = String.fromCString(sqlite3_errmsg(db))
    println("error preparing '\(query)': \(errmsg!)")
    return false
  }

  func bind(parm:Int, value:String) -> Bool {
    if sqlite3_bind_text(statement, Int32(parm), value, -1, SQLITE_TRANSIENT) == SQLITE_OK { return true }
    let errmsg = String.fromCString(sqlite3_errmsg(db))
    println("failure binding foo: \(errmsg!)")
    return false
  }

  func execute() -> Bool {
    if sqlite3_step(statement) == SQLITE_DONE { return true }
    let errmsg = String.fromCString(sqlite3_errmsg(db))
    println("failure in execute: \(errmsg!)")
    return false
  }

  func lastId() -> Int {
    return Int(sqlite3_last_insert_rowid(db))
  }

  func nextRow() -> Bool {
    if sqlite3_step(statement) == SQLITE_ROW { return true }
    statement = nil
    return false
  }

  func intAt(col:Int) -> Int {
    return Int(sqlite3_column_int64(statement, Int32(col)))
  }

  func textAt(col:Int) -> String {
    let name = sqlite3_column_text(statement, Int32(col))
    if name != nil {
      return String.fromCString(UnsafePointer<Int8>(name))!
    }
    return ""
  }

}

，然后在单个类中:

let sqLite = SQLite.sharedInstance
sqLite.select("* FROM table")
while sqLite.nextRow() { 
  println(sqLite.textAt(0))
}

我想其余的都是显而易见的.

I guess the rest is obvious.

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