(Objective-C) Streaming Download Large File to the Local Filesystem

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

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

// 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".
BOOL 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: 2020-08-04" header to be automatically added.
azAuth.XMsVersion = @"2020-08-04";
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);
    }

}