Question

我正在开发一个我想下载某些文件的应用程序。

如果要下载的文件是图片，我只需下载
如果要下载的文件是视频，我需要触发另一个缩略图下载

为此，我使用的是NSURLSessionDownloadTask。使用图像一切正常但是当涉及到视频时，视频本身会正确下载，但是thumbanil总是会返回错误：

错误：网址不兼容

以下是代码：

- (void)download:(Message)message
               completion:(void (^)(NSArray *))completion {

NSString *mediaURL = [NSString stringWithUTF8String: message.remoteMediaUrl()];

__block BOOL isVideo = NO;
NSString* mimeType = [NSString stringWithUTF8String:message.mediaMimeType()];
if ([mimeType hasPrefix:@"video/"])
    isVideo = YES;

NSString *mediaName = [mediaURL lastPathComponent];
NSURL *URL = [NSURL URLWithString:mediaURL];
NSURLRequest *request = [NSURLRequest requestWithURL:URL];
NSString *user = [self.user];
NSString *password = [self.password];

[self.manager setTaskDidReceiveAuthenticationChallengeBlock:^NSURLSessionAuthChallengeDisposition(NSURLSession * _Nonnull session, NSURLSessionTask * _Nonnull task, NSURLAuthenticationChallenge * _Nonnull challenge, NSURLCredential *__autoreleasing  _Nullable * _Nullable credential) {
    NSString *authenicationMethod = challenge.protectionSpace.authenticationMethod;
    if ([authenicationMethod isEqualToString:NSURLAuthenticationMethodHTTPDigest]) {
        *credential = [NSURLCredential credentialWithUser:user password:password persistence:NSURLCredentialPersistenceForSession];
        return NSURLSessionAuthChallengeUseCredential;
    }
    return NSURLSessionAuthChallengeCancelAuthenticationChallenge;
}];

NSURLSessionDownloadTask *downloadTask = [self.manager downloadTaskWithRequest:request progress:nil destination:^NSURL *(NSURL *targetPath, NSURLResponse *response) {

    NSURL *fileURL = [[ContentService imageDownloadDirectoryURL] URLByAppendingPathComponent: mediaName];
    [[NSFileManager defaultManager] removeItemAtURL:fileURL error:nil];

    fileURL = [fileURL URLByAppendingPathExtension:[self getExtensionFromMimeType:message.mediaMimeType()]];
    return fileURL;
} completionHandler:^(NSURLResponse *response, NSURL *fileURL, NSError *error) {
    if (error != nil) {
        NSLog(@"Error: %@", [error localizedDescription]);
        completion(nil);
    } else {
        NSLog(@"File downloaded to: %@ ", fileURL);
    ////////////////////////////////////////////////
        if (isVideo) {
            NSLog(@"Download thumbnail for video");
            isVideo = NO;
            NSString *thumbnailURLAsString = [NSString stringWithUTF8String: message.remoteThumbnailUrl()];
            NSString *thumbnailName = [thumbnailURLAsString lastPathComponent];
            NSURL *thumbnailURL = [NSURL URLWithString:thumbnailName];

            NSURLRequest *thumbnailRequest = [NSURLRequest requestWithURL:thumbnailURL];
            NSURLSessionDownloadTask *thDownloadTask = [self.manager downloadTaskWithRequest:thumbnailRequest progress:nil destination:^NSURL *(NSURL *targetPath2, NSURLResponse *thresponse) {

                NSURL *thumbnailfileURL = [[ContentService imageDownloadDirectoryURL] URLByAppendingPathComponent: thumbnailName];
                [[NSFileManager defaultManager] removeItemAtURL:thumbnailfileURL error:nil];
                return thumbnailfileURL;
            } completionHandler:^(NSURLResponse *thresponse, NSURL *thumbnailfileURL, NSError *error) {
                if (error != nil) {
                    NSLog(@"Error: %@", [error localizedDescription]);
                    completion(nil);
                } else {
                    NSLog(@"File downloaded to: %@", thumbnailfileURL);
                    completion([NSArray arrayWithObjects:fileURL, thumbnailfileURL,nil]);
                }
            }];
            [thDownloadTask resume];
        } // if isVideo 
       //////////////////////////
        else {
            completion([NSArray arrayWithObjects:fileURL, nil]);
        }
    }
}];
[downloadTask resume];

}

我知道代码会重复，但是现在我想要有一些工作。有人能告诉我出了什么问题吗？

此外，如果这种方法不正确，我应该使用哪一种？

提前致谢并问候

使用NSURLSessionDownloadTask

0 个答案: