Ios 不能'；t通过NSOutputStream将数据保存在文档目录的给定路径中

如何通过NSOutputStream将下载的内容/数据保存在文档目录的给定路径中。如果我用DD附加文件名，那么它可以工作（ex-DD/contentPath.zip），但是如果我附加像DD/hello/contentPath.zip这样的路径，那么它就不能工作。为什么？我试着像下面一样-

- (void) downloadCarContents:(NSString *)url forContent:(NSString *)contentPath {

    //NSString *destinationPath = [self.documentDirectory getDownloadContentPath:contentPath];

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    AFHTTPRequestOperation *op = [manager GET:url
                                   parameters:nil
                                      success:^(AFHTTPRequestOperation *operation, id responseObject) {


                                      } failure:^(AFHTTPRequestOperation *operation, NSError *error) {

                                          //NSLog(@"Error : %@", error.localizedDescription);
                                      }];

    NSString *documentsDirectory = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *dest = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"hello/%@.zip", contentPath]];// It doesn't work
    //NSString *dest = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.zip", contentPath]];// It works

    op.outputStream = [NSOutputStream outputStreamToFileAtPath:dest append:NO];

    [op setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead) {
        float percentage = (float) (totalBytesRead * 100) / totalBytesExpectedToRead;
        [self.delegate downloadProgression:percentage];
    }];
}

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API不会为您创建文件夹。您的代码在尝试使用它之前需要确保它存在

NSFileManager

可以帮助