iOS：从网址下载图片并保存在设备中 [英] iOS: Download image from url and save in device

问题描述

我尝试从网址下载图片 http：//a3.twimg .com / profile_images / 414797877 / 05052008321_bigger.jpg

I am trying to download the image from the url http://a3.twimg.com/profile_images/414797877/05052008321_bigger.jpg

我使用以下代码，但图片未保存在设备中。我想知道我做错了什么。

I am using the following code, but image is not saved in the device. I want to know what I am doing wrong.

 NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://a3.twimg.com/profile_images/414797877/05052008321_bigger.jpg"]];
 [NSURLConnection connectionWithRequest:request delegate:self];

 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
 NSString *documentsDirectory = [paths objectAtIndex:0];
 NSString *localFilePath = [documentsDirectory stringByAppendingPathComponent:@"pkm.jpg"];
 NSData *thedata = NULL;
 [thedata writeToFile:localFilePath atomically:YES];

 UIImage *img = [[UIImage alloc] initWithData:thedata];

推荐答案

如果设置 / code>到 nil ，你期望它写入磁盘是什么？

If you set theData to nil, what do you expect it to write to the disk?

可以使用 NSData * theData = [NSData dataWithContentsOfURL：yourURLHere]; 从磁盘加载数据，然后使用 writeToFile：atomically： / code>。如果您需要更多控制加载进程或在后台进行，请查看 NSURLConnection 及相关指南的文档。

What you can use is NSData* theData = [NSData dataWithContentsOfURL:yourURLHere]; to load the data from the disk and then save it using writeToFile:atomically:. If you need more control over the loading process or have it in background, look at the documentation of NSURLConnection and the associated guide.

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