(Objective-C) (using AWS Signature Version 2) Streaming Download to File

The main purpose of this example is to demonstrate how to use the older Signature Version 2 authentication w/ S3. It uses V2 authentication to download a file.

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

// 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 Amazon AWS REST server.
BOOL bTls = YES;
int port = 443;
BOOL bAutoReconnect = YES;
// The file is located in the bucket named "chilkat100", which becomes part of the domain:
BOOL success = [rest Connect: @"chilkat100.s3.amazonaws.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];

// Provide AWS credentials for the REST call.
CkoAuthAws *authAws = [[CkoAuthAws alloc] init];
authAws.AccessKey = @"AWS_ACCESS_KEY";
authAws.SecretKey = @"AWS_SECRET_KEY";
authAws.ServiceName = @"s3";

// For AWS Signature Version 2, the following two properties need to be set:
authAws.SignatureVersion = [NSNumber numberWithInt:2];
// See http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#ConstructingTheCanonicalizedResourceElement
authAws.CanonicalizedResourceV2 = @"/chilkat100/starfish.jpg";

success = [rest SetAuthAws: authAws];

// Send the request to download the JPG.
success = [rest SendReqNoBody: @"GET" uriPath: @"/starfish.jpg"];
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 JPG 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/starfish.jpg";

    // 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 JPG file.");

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

}