Four Common Data Persistence methods in IOS and four data persistence methods in ios

Four Common Data Persistence methods in IOS and four data persistence methods in ios

• (1) attribute list: simple, applicable only to small data volumes
• (2) object Archiving: encryption and storage are serialized and can only be applied to small data volumes.
• (3) SQLite: SQLite is portable, easy to use, small, efficient, and reliable.
• (4) CoraData: Core Data uses SQLite to store Data, but it does not need to write any SQL statements.

1. property list: container object --> property list: Save the array to the sandbox path.

2. Object Archiving: serialize data

3. SQLite

• -(Void) copyDBFile

  {

  NSFileManager * manager = [NSFileManager defamanager manager];

  // If the file exists, it will not be copied

  If ([manager fileExistsAtPath: [self databasePath]) {

  Return;

  }

  NSString * atPath = [[NSBundle mainBundle] pathForResource: kDatabaseName ofType: nil];

  // Copy the database file to the sandbox path

  [Manager copyItemAtPath: atPath toPath: [self databasePath] error: nil];

  }

  
  

  // Obtain the path of the database file

  -(NSString *) databasePath

  {

  // NSLog (@ "% @", [[NSBundle mainBundle] pathForResource: kDatabaseName ofType: nil]);

  Return [NSHomeDirectory () stringByAppendingFormat: @ "/Library/% @", kDatabaseName];

  // Return [[NSBundle mainBundle] pathForResource: kDatabaseName ofType: nil];

  }

  
  

  // Add a data entry

  -(BOOL) addUser :( User *) user

  {

  // Database object

  Sqlite3 * mysqlite = nil;

  
  

  // 1. Open the database

  // Filename: Path of the database file (string of C)

  // Sqlite3: database object to be executed

  Int openResult = sqlite3_open ([[self databasePath] UTF8String], & mysqlite );

  // If the open function is successfully executed, 0 and SQLITE_ OK are returned.

  If (openResult! = SQLITE_ OK ){

  NSLog (@ "database opening failed ");

  Return NO;

  }

  // 2. Prepare SQL statements

  // You can regard the content stored in sqlite3_stmt * as an SQL statement.

  Sqlite3_stmt * stmt = nil;

  // Construct an SQL statement

  NSString * SQL = [NSString stringWithFormat: @ "insert into UserTable (username, password, phone, age) values (\" % @ \ ", \" % @\", \ "% @ \", % ld) ", user. username, user. password, user. phone, user. age];

  // Sqlite3: database object to be executed

  // ZSql: SQL statement

  // Stmt: Object saved by the statement

  Sqlite3_prepare (mysqlite, [SQL UTF8String],-1, & stmt, NULL );

  // 3. Execute the SQL statement

  Int stepResult = sqlite3_step (stmt );

  If (stepResult = SQLITE_ERROR | stepResult = SQLITE_MISUSE ){

  NSLog (@ "execution failed ");

  }

  // 4. SQL statement completion

  Sqlite3_finalize (stmt );

  // 5. Close the database

  Sqlite3_close (mysqlite );

  Return YES;

  }

  4. CoreData

  -(Void) openDataBase

  {

  // 1. Load the data model file xcdatamodeld

  NSURL * url = [[NSBundle mainBundle] URLForResource: @ "DataModel" withExtension: @ "momd"];

  // NSManagedObjectModel is used to load the data model file.

  NSManagedObjectModel * dataModel = [[NSManagedObjectModel alloc] initWithContentsOfURL: url];

  // 2. Open the database file corresponding to the model file

  // Create a coordinator object and use the Coordinator to manage database files

  NSPersistentStoreCoordinator * psc = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: dataModel];

  // Specify the location of the database file in the sandbox

  NSString * storePath = [NSHomeDirectory () stringByAppendingString: @ "/Documents/DataStore. sqlite"];

  NSURL * storeURL = [NSURL fileURLWithPath: storePath];

  // Open a data file PersistentStore --> database file

  /*

  1. If the file does not exist, create a new database file.

  2. If the file exists, open the file directly.

  */

  NSError * error = nil;

  [Psc addPersistentStoreWithType: NSSQLiteStoreType // The generated database file format is SQLite

  Configuration: nil

  URL: storeURL // path for storing database files

  Options: nil

  Error: & error];

  If (error ){

  NSLog (@ "database file opening failed ");

  } Else

  {

  NSLog (@ "database opened successfully ");

  }

  // 3. Operate the database

  Context = [[NSManagedObjectContext alloc] init];

  // Specifies which coordinator the context uses to Operate Database Files

  Context. persistentStoreCoordinator = psc;

  }