在 iOS 中使用 AFNetworking 下载文件/图像? [英] Download a file / image with AFNetworking in iOS?

问题描述

我以为我已经弄明白了，但我就是无法让它工作.我有一个在数组中的每个 URL 上调用的方法.此方法具有图片的 URL，应将其下载到 Application Support 文件夹中的特定路径中以供离线使用.但也许我误解了 AFNetwork 库中的方法.我的方法是这样的:

I thought I had it figured out but I just can't get it to work. I have a method that is called on every URL in an array. This method have a URL of a picture that should be downloaded in specific path in a Application Support folder for offline use. But maybe I'm misinterpreting the methods in the AFNetwork library. My method looks like this:

- (void) downloadImageInBackground:(NSDictionary *)args{

  @autoreleasepool {

    NSString *photourl = [args objectForKey:@"photoUrl"];
    NSString *articleID = [args objectForKey:@"articleID"];
    NSString *guideName = [args objectForKey:@"guideName"];
    NSNumber *totalNumberOfImages = [args objectForKey:@"totalNumberOfImages"];

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photourl]];

    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    operation.inputStream = [NSInputStream inputStreamWithURL:[NSURL URLWithString:photourl]];

    [operation setShouldExecuteAsBackgroundTaskWithExpirationHandler:^{
        DLog(@"PROBLEMS_AF");
    }];
    DLog(@"URL_PHOTOURL: %@", photourl);
    DLog(@"indexSet: %@", operation.hasAcceptableStatusCode); 
    [operation  response];

    NSData *data = [args objectForKey:@"data"];

    NSString *path;
    path = [NSMutableString stringWithFormat:@"%@/Library/Application Support/Guides", NSHomeDirectory()];
    path = [path stringByAppendingPathComponent:guideName];
    NSString *guidePath = path;
    path = [path stringByAppendingPathComponent:photourl];

    if ([[NSFileManager defaultManager] fileExistsAtPath:guidePath]){
        [[NSFileManager defaultManager] createFileAtPath:path
                                                contents:data
                                              attributes:nil];
    }

    DLog(@"path: %@", path);
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];
    [operation start];


    DLog(@"isExecuting: %d",[operation isExecuting]);
    DLog(@"IS_FINISHED: %d",[operation isFinished]);


  }

} 

PhotoURL 是指向我要下载的图像的直接链接.

PhotoURL is the direct link to the image that I want to download.

由于对所有图像都调用了此方法，因此所有日志都调用了多次，似乎是正确的.

Since this method is called for all the images, all logs is called several times, and seems to be correct.

推荐答案

您在这里遇到了一些问题.那么首先，你为什么使用 @autoreleasepool?我认为这里没有必要.另外，你在使用ARC吗?我认为这一点，对于我其余的回答.

You have a few problems here. so first, why are you using @autoreleasepool? i think there is no need for this here. also, are you using ARC? i consider this, for the rest of my answer.

在 AFNetworking 中有一个名为 AFImageRequestOperation 的类，所以这对您来说是个好主意.首先，导入它

in AFNetworking there is a class called AFImageRequestOperation , so this would be a good idea for you to use. first, import it

#import "AFImageRequestOperation.h"

然后你可以创建一个对象

then you could create an object

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photourl]];
AFImageRequestOperation *operation;
operation = [AFImageRequestOperation imageRequestOperationWithRequest:request 
    imageProcessingBlock:nil 
    cacheName:nil 
    success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

    } 
    failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
        NSLog(@"%@", [error localizedDescription]);
    }];

现在，在成功块中，您获得了所需的 UIImage.在那里您需要获取文档目录.您的代码将无法在 ios 设备上运行.

now, in the success block, you got the UIImage you need. there you need to get the documents directory. your code will not work on an ios device.

// Get dir
NSString *documentsDirectory = nil;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
documentsDirectory = [paths objectAtIndex:0];
NSString *pathString = [NSString stringWithFormat:@"%@/%@",documentsDirectory, guideName];

然后你可以使用 NSDatas writeToFile

and then you could use NSDatas writeToFile

// Save Image
NSData *imageData = UIImageJPEGRepresentation(image, 90);
[imageData writeToFile:pathString atomically:YES];

最后，您需要开始操作

[operation start];

一起:

- (void)downloadImageInBackground:(NSDictionary *)args{

    NSString *guideName = [args objectForKey:@"guideName"];
    NSString *photourl = [args objectForKey:@"photoUrl"];

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:photourl]];

    AFImageRequestOperation *operation = [AFImageRequestOperation imageRequestOperationWithRequest:request 
        imageProcessingBlock:nil 
        cacheName:nil 
        success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {

            // Get dir
            NSString *documentsDirectory = nil;
            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            documentsDirectory = [paths objectAtIndex:0];
            NSString *pathString = [NSString stringWithFormat:@"%@/%@",documentsDirectory, guideName];

            // Save Image
            NSData *imageData = UIImageJPEGRepresentation(image, 90);
            [imageData writeToFile:pathString atomically:YES];

        } 
        failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
            NSLog(@"%@", [error localizedDescription]);
        }];

    [operation start];
}

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