如何从url下载文件并存储在文档文件夹中 [英] how to download files from url and store in document folder

问题描述

我创建了一个具有两个页面的应用程序（第一页显示数据列表，第二页显示详细数据）。

I created one application that has two page (first page for show list of data and second page for show detail data).

当单击任何单元格时下一页和下一页存在一个名称为：DOWNLOAD
的按钮，当我点击该按钮此文件下载并保存在文档文件夹中时。
我不知道。请指导我如何下载任何文件并存储在文件夹中。
我在互联网上搜索，但我不了解它。

when click on any cell go to next page and in next page exists one button with name : DOWNLOAD that I want when I click on that button this file download and save in document folder. I dont know about it. please guide me that how download any file and store in document folder. I searching in internet but I dont understand about it.

请告诉我如何使用一个按钮下载任何文件的代码。对不起，如果我不是很好的英语

please tell me with code that how downloaded any file with one button. Im sorry if I not good english.

推荐答案

这是我简单的朋友，

NSString *stringURL = @"http://www.somewhere.com/thefile.png";
NSURL  *url = [NSURL URLWithString:stringURL];
NSData *urlData = [NSData dataWithContentsOfURL:url];
if ( urlData )
{
  NSArray       *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString  *documentsDirectory = [paths objectAtIndex:0];  

  NSString  *filePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory,@"filename.png"];
  [urlData writeToFile:filePath atomically:YES];
}

建议在单独的线程中执行代码。 em>

it advisable to execute the code in a separate thread.

编辑1：更多信息

1）对于大文件下载，

1) for large file downloads,

-(IBAction) downloadButtonPressed:(id)sender;{
    //download the file in a seperate thread.
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSLog(@"Downloading Started");
        NSString *urlToDownload = @"http://www.somewhere.com/thefile.png";
        NSURL  *url = [NSURL URLWithString:urlToDownload];
        NSData *urlData = [NSData dataWithContentsOfURL:url];
        if ( urlData )
        {
            NSArray       *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString  *documentsDirectory = [paths objectAtIndex:0];

            NSString  *filePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory,@"filename.png"];

            //saving is done on main thread
            dispatch_async(dispatch_get_main_queue(), ^{
                [urlData writeToFile:filePath atomically:YES];
                NSLog(@"File Saved !");
            });
        }

    });

}

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