Objective-C

Streaming Download Large File to the Local Filesystem

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Downloads a large file in a streaming fashion to the local filesystem. Objective-C

#import <CkoRest.h>
#import <CkoAuthAzureStorage.h>
#import <CkoStream.h>
#import <NSString.h>

BOOL success = NO;

//  Azure File Service Example: Downloads a large file to the local filesystem using a Chilkat stream.
//  See:  https://docs.microsoft.com/en-us/rest/api/storageservices/get-file

//  This example requires the Chilkat API to have been previously unlocked.
//  See Global Unlock Sample for sample code.

CkoRest *rest = [[CkoRest alloc] init];

//  Connect to the Azure Storage Blob Service
BOOL bTls = YES;
int port = 443;
BOOL bAutoReconnect = YES;
//  In this example, the storage account name is "chilkat".
success = [rest Connect: @"chilkat.file.core.windows.net" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

//  Provide Azure Cloud credentials for the REST calls.
CkoAuthAzureStorage *azAuth = [[CkoAuthAzureStorage alloc] init];
azAuth.AccessKey = @"AZURE_ACCESS_KEY";
//  The account name used here should match the 1st part of the domain passed in the call to Connect (above).
azAuth.Account = @"chilkat";
azAuth.Scheme = @"SharedKey";
azAuth.Service = @"File";
//  This causes the "x-ms-version: 2021-08-06" header to be automatically added.
azAuth.XMsVersion = @"2021-08-06";
success = [rest SetAuthAzureStorage: azAuth];

//  Note: The application does not need to explicitly set the following
//  headers: x-ms-date, Authorization.  These headers
//  are automatically set by Chilkat.

//  When streaming a download to the local filesystem or directed elsewhere,
//  the complete HTTP GET operation must be broken into parts.
//  For example, an HTTP GET consists of sending the request, followed by reading the response header,
//  and then finally the response body.  We'll want to read the response header, and then based
//  on the information received (such as success or failure), either read the response body
//  as an error message, or as the file data.

//  Send the HTTP GET request to download the file.
//  The share is named "pip".
success = [rest SendReqNoBody: @"GET" uriPath: @"/pip/somethingBig.zip"];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

//  Read the response header.
int responseStatusCode = [[rest ReadResponseHeader] intValue];
if (responseStatusCode < 0) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

NSLog(@"%@%d",@"Response status code = ",responseStatusCode);

//  We expect a 200 response status if the file data is coming.
//  Otherwise, we'll get a string response body with an error message(or no response body).
if (responseStatusCode == 200) {

    CkoStream *bodyStream = [[CkoStream alloc] init];

    //  The stream's sink will be a file.
    bodyStream.SinkFile = @"qa_output/somethingBig.zip";

    //  Read the response body to the stream.  Given that we've
    //  set the stream's sink to a file, it will stream directly
    //  to the file.
    success = [rest ReadRespBodyStream: bodyStream autoSetStreamCharset: YES];
    if (success != YES) {
        NSLog(@"%@",rest.LastErrorText);
        return;
    }

    NSLog(@"%@",@"Successfully received the large file.");

}
else {
    NSString *errResponse = [rest ReadRespBodyString];
    if (rest.LastMethodSuccess != YES) {
        NSLog(@"%@",rest.LastErrorText);
    }
    else {
        NSLog(@"%@",errResponse);
    }

}