第三篇、FMDB使用

简介：

　　FMDB是基于SQlite3的封装一个第三方的OC库，操作起来更加简单，性能比Coredata更加高。

1.创建sqlite文件

2.导入FMDB头文件

3.创建数据库表table

4.编写sql语句

5.执行操作语句

1.使用示例：

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.
        SQLiteManager.shareManager().openDB("hjq.sqlite")

        return true
    }
}

2.创建数据库并建表

import UIKit

class SQLiteManager: NSObject {

/// 单例
    private static let manager: SQLiteManager = SQLiteManager()
    class func shareManager() -> SQLiteManager {
        return manager
    }

    var dbQueue: FMDatabaseQueue?

    /**
    *  打开数据库
    */
    func openDB(DBName: String)
    {
        // 1.根据传入的数据库名称拼接数据库路径
        let path = DBName.docDir()
        print(path)

        // 2.创建数据库对象
        // 注意: 如果是使用FMDatabaseQueue创建数据库对象, 那么就不用打开数据库
        dbQueue = FMDatabaseQueue(path: path)

        // 4.创建表
        creatTable()
    }
    
    private func creatTable()
    {
        // 1.编写SQL语句
        let sql = "CREATE TABLE IF NOT EXISTS T_Person( \n" +
            "id INTEGER PRIMARY KEY AUTOINCREMENT, \n" +
            "name TEXT, \n" +
            "age INTEGER \n" +
        "); \n"

        // 2.执行SQL语句
        dbQueue!.inDatabase { (db) -> Void in
            db.executeUpdate(sql, withArgumentsInArray: nil)
        }
    }
}

3.插入数据

        // 1.定义SQL语句
        let sql = "INSERT OR REPLACE INTO T_Status" +
            "(statusId, statusText, userId)" +
            "VALUES" +
            "(?, ?, ?);"

        // 2.执行SQL语句（用事务）
        SQLiteManager.shareManager().dbQueue?.inTransaction({ (db, rollback) -> Void in

            for dict in statuses
            {
                let statusId = dict["id"]!
                // JSON -> 二进制 -> 字符串
                let data = try! NSJSONSerialization.dataWithJSONObject(dict, options: NSJSONWritingOptions.PrettyPrinted)
                let statusText = String(data: data, encoding: NSUTF8StringEncoding)!
                print(statusText)
                if !db.executeUpdate(sql, statusId, statusText, userId)
                {
                    // 如果插入数据失败, 就回滚
                    rollback.memory = true
                }

            }
        })

4.查找数据

        // 1.定义SQL语句
        var sql = "SELECT * FROM T_Status \n"
        if since_id >
        {
            sql += "WHERE statusId > \(since_id) \n"
        }else if max_id >
        {
            sql += "WHERE statusId < \(max_id) \n"
        }

        sql += "ORDER BY statusId DESC \n"
        sql += "LIMIT 20; \n"

        // 2.执行SQL语句
        SQLiteManager.shareManager().dbQueue?.inDatabase({ (db) -> Void in

            // 2.1查询数据
            // 返回字典数组的原因:通过网络获取返回的也是字典数组,
            // 让本地和网络返回的数据类型保持一致, 以便于我们后期处理
            var statuses = [[String: AnyObject]]()

            if let res =  db.executeQuery(sql, withArgumentsInArray: nil)
            {
                // 2.2遍历取出查询到的数据
                while res.next()
                {
                    // 1.取出数据库存储的一条微博字符串
                    let dictStr = res.stringForColumn("statusText") as String
                    // 2.将微博字符串转换为微博字典
                    let data = dictStr.dataUsingEncoding(NSUTF8StringEncoding)!
                    let dict = try! NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers) as! [String: AnyObject]
                    statuses.append(dict)
                }

                // 3.返回数据
                finished(statuses)

            }

            // 3.返回数据
            finished(statuses)

        })

5.删除和更新

        // 1.定义SQL语句
        let sql = "DELETE FROM T_Status WHERE createDate  <= '\(dateStr)';"

        // 2.执行SQL语句
        SQLiteManager.shareManager().dbQueue?.inDatabase({ (db) -> Void in
            db.executeUpdate(sql, withArgumentsInArray: nil)
        })

附：

String分类获取文件目录

import UIKit

extension String{
    /**
    将当前字符串拼接到cache目录后面
    */
    func cacheDir() -> String{
        let path = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.CachesDirectory, NSSearchPathDomainMask.UserDomainMask, true).last!  as NSString
        return path.stringByAppendingPathComponent((self as NSString).lastPathComponent)
    }
    /**
    将当前字符串拼接到doc目录后面
    */
    func docDir() -> String
    {
        let path = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true).last!  as NSString
        return path.stringByAppendingPathComponent((self as NSString).lastPathComponent)
    }
    /**
    将当前字符串拼接到tmp目录后面
    */
    func tmpDir() -> String
    {
        let path = NSTemporaryDirectory() as NSString
        return path.stringByAppendingPathComponent((self as NSString).lastPathComponent)
    }
}