数据持久化

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在模拟器中运行iOS程序，都会为该程序创建一个沙盒（SandBox）。想要找到沙盒目录，先运行Finder，然后在Finder的菜单栏找到前往—前往文件夹…，在打开的窗口输入

ios7之前

/Users/dante/Library/Application Support/iPhone Simulator/6.1/Applications/4FD4E9ED-EFAF-495A-8BA8-653DC43E8C8E/Documents/play.mp4

ios7之后

/Users/mac/Library/Developer/CoreSimulator/Devices/A747DC96-ED64-4E1F-AB15-8EC65E015F9D/data/Containers/Data/Application/B4864589-CBAA-4964-B993-146A99764188/Documents/play.mp4

其中，mac是指用户在Mac系统中的用户名。

    //获得路径

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSString *fullpath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"play.mp4"];

    NSLog(@"%@",fullpath);

    //取出路径的内容

    NSData *cityData = [NSData dataWithContentsOfFile:fullpath];

    //如果本地已有数据就不再请求

    if (cityData)

    {

        self.playerController=[[MPMoviePlayerViewController alloc] init];

        [self presentMoviePlayerViewControllerAnimated:self.playerController];

        [self.playerController.moviePlayer play];

    }

    else

    {

        //下载到本地

        NSURL *url = [NSURL URLWithString:@"http://vdata.tool.hexun.com/2013-07-15/156151759_m.mp4"];

        //把数据写入属性列表

        //获得路径

        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

        NSString *fullpath = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"play.mp4"];

        NSData *data=[[NSData alloc]initWithContentsOfURL:url];

        [data writeToFile:fullpath atomically:YES];

    }

数据持久化

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原文地址：http://www.cnblogs.com/huangzs/p/4463498.html