用swift保存sqlite数据库

Question

完成本教程后

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

我发现数据库只是在应用程序运行时创建的。第二次运行应用程序时如何访问数据库。而我的最终目标是创建一个数据库并使用这些数据来展示事物。

Answer 1

我使用以下简单的包装器：

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))
}

我想其余的很明显。