如何使用 AFNetworking 下载文件并将其保存到文档目录？

Question

我正在使用 AFNetworking 库。我不知道如何下载文件并将其保存到文档目录。

Answer 1

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"..."]];
AFHTTPRequestOperation *operation = [[[AFHTTPRequestOperation alloc] initWithRequest:request] autorelease];

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"filename"];
operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];

[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"Successfully downloaded file to %@", path);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

[operation start];

Answer 2

我要跳出@mattt 的回答，并使用AFHTTPRequestOperationManager 发布AFNetworking 2.0 的版本。

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *path = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"filename"];

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
AFHTTPRequestOperation *op = [manager GET:@"http://example.com/file/to/download" 
                               parameters:nil
    success:^(AFHTTPRequestOperation *operation, id responseObject) {
         NSLog(@"successful download to %@", path);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
         NSLog(@"Error: %@", error);
    }];
op.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];

Answer 3

我说的是AFNetworking 2.0

[AFHTTPRequestOperationManager manager] 使用默认的 AFJSONResponseSerializer 创建管理器对象，并执行内容类型限制。看看这个

- (BOOL)validateResponse:(NSHTTPURLResponse *)response
                    data:(NSData *)data
                   error:(NSError * __autoreleasing *)error

所以我们需要创建一个无响应序列化程序并像往常一样使用AFHTTPRequestOperationManager。

这里是 AFNoneResponseSerializer

@interface AFNoneResponseSerializer : AFHTTPResponseSerializer

+ (instancetype)serializer;

@end

@implementation AFNoneResponseSerializer

#pragma mark - Initialization
+ (instancetype)serializer
{
    return [[self alloc] init];
}

- (instancetype)init
{
    self = [super init];

    return self;
}

#pragma mark - AFURLResponseSerializer
- (id)responseObjectForResponse:(NSURLResponse *)response
                           data:(NSData *)data
                          error:(NSError *__autoreleasing *)error

{
    return data;
}

@end

用法

self.manager = [AFHTTPRequestOperationManager manager];
self.manager.responseSerializer = [AFNoneResponseSerializer serializer];

[self.manager GET:@"https://sites.google.com/site/iphonesdktutorials/xml/Books.xml"
           parameters:parameters
              success:^(AFHTTPRequestOperation *operation, id responseObject)
    {
        if (success) {
            success(responseObject);
        }
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        if (failure) {
            failure(error);
        }
    }];

这样我们就可以得到整个文件而无需任何序列化

Answer 4

Documentation page 有“创建下载任务”部分的示例：

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

NSURL *URL = [NSURL URLWithString:@"http://example.com/download.zip"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];

NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {
    NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
    return [documentsDirectoryURL URLByAppendingPathComponent:[response suggestedFilename]];
} completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
    NSLog(@"File downloaded to: %@", filePath);
}];
[downloadTask resume];

注意！代码适用于 iOS 7+（使用 AFNetworking 2.5.1 测试）

Answer 5

来自AFNetworking 文档。 将加载的文件保存到您的文档中。 AFNetworking 3.0

NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];

NSURL *URL = [NSURL URLWithString:@"http://example.com/download.zip"];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];

NSURLSessionDownloadTask *downloadTask = [manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {
    NSURL *documentsDirectoryURL = [[NSFileManager defaultManager] URLForDirectory:NSDocumentDirectory inDomain:NSUserDomainMask appropriateForURL:nil create:NO error:nil];
    return [documentsDirectoryURL URLByAppendingPathComponent:[response suggestedFilename]];
} completionHandler:^(NSURLResponse *response, NSURL *filePath, NSError *error) {
    NSLog(@"File downloaded to: %@", filePath);
}];
[downloadTask resume];

Answer 6

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];

manager.responseSerializer = [AFCompoundResponseSerializer serializer];

manager.responseSerializer.acceptableContentTypes = [NSSet setWithObject:@"application/octet-stream"];

AFHTTPRequestOperation *operation = [manager GET:url   parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
    if (responseObject) {
        // your code here
    } else {
        // your code here
    }
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {

}];

[operation start];

// manager.responseSerializer.acceptableContentTypes = [NSSet setWithObject:@"application/octet-stream"];可能因您的期望而异

Answer 7

是的，最好使用AFNetworking 2.0 方式和AFHTTPRequestOperationManager。使用旧方式我的文件确实下载了，但由于某种原因没有在文件系统中更新。

附加到 swilliam 的 答案以显示下载进度，在 AFNetworking 2.0 中您也可以这样做 - 只需在设置输出流后设置下载进度块。

__weak SettingsTableViewController *weakSelf = self;

operation.outputStream = [NSOutputStream outputStreamToFileAtPath:newFilePath append:NO];

[operation setDownloadProgressBlock:^(NSUInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToRead) {

    float progress = totalBytesWritten / (float)totalBytesExpectedToRead;

    NSString *progressMessage = [NSString stringWithFormat:@"%@ \n %.2f %% \n %@ / %@", @"Downloading ...", progress * 100, [weakSelf fileSizeStringWithSize:totalBytesWritten], [weakSelf fileSizeStringWithSize:totalBytesExpectedToRead]];

    [SVProgressHUD showProgress:progress status:progressMessage];
}];

这是我创建字节字符串的方法：

- (NSString *)fileSizeStringWithSize:(long long)size
{
    NSString *sizeString;
    CGFloat f;

    if (size < 1024) {
        sizeString = [NSString stringWithFormat:@"%d %@", (int)size, @"bytes"];
    }
    else if ((size >= 1024)&&(size < (1024*1024))) {
        f = size / 1024.0f;
        sizeString = [NSString stringWithFormat:@"%.0f %@", f, @"Kb"];
    }
    else if (size >= (1024*1024)) {
        f = size / (1024.0f*1024.0f);
        sizeString = [NSString stringWithFormat:@"%.0f %@", f, @"Mb"];
    }

    return sizeString;
}

Answer 8

除了之前的答案，对于 AFNetworking 2.5.0 和 iOS7/8，我发现还需要额外的打开输出流的步骤来防止应用挂起（并最终因内存不足而崩溃） .

operation.outputStream = [NSOutputStream outputStreamToFileAtPath:dest
                                                          append:NO];
[operation.outputStream open];
[operation start];