Objective-C

REST Read Response with Stream API

See more REST Examples

Demonstrates how to make a REST call that returns a binary body, and to receive the body through a stream API. Objective-C

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

BOOL success = NO;

// 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;
success = [rest Connect: @"s3.amazonaws.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];

// ----------------------------------------------------------------------------
// Important: For buckets created in regions outside us-east-1,
// there are three important changes that need to be made.
// See Working with S3 Buckets in Non-us-east-1 Regions for the details.
// ----------------------------------------------------------------------------

// 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";
success = [rest SetAuthAws: authAws];

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat100".
rest.Host = @"chilkat100.s3.amazonaws.com";

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

    return;
}

CkoStream *bodyStream = [[CkoStream alloc] init];
// Set a 10 second read timeout for the stream. 
// (Give up if no data arrives within 10 seconds after calling a read method.)
bodyStream.ReadTimeoutMs = [NSNumber numberWithInt:10000];

// Create a background thread task to read the response body (which feeds
// it to the bodyStream object.)
CkoTask *readResponseBodyTask = [rest ReadRespBodyStreamAsync: bodyStream autoSetStreamCharset: YES];

// Start the task. 
success = [readResponseBodyTask Run];

// The application can now read the bodyStream...
while ((bodyStream.EndOfStream != YES)) {

    // Read the next chunk of bytes (whatever is immediately available,
    // or wait for more data (up to 10 seconds because we set the stream's ReadTimeoutMs property)
    NSData nextChunk = [bodyStream ReadBytes];
    if (bodyStream.LastMethodSuccess != YES) {
        NSLog(@"%@",@"Failed to receive more response data.");
        // Make sure the background task is aborted/cancelled.
        success = [readResponseBodyTask Cancel];

        return;
    }

    // OK.. the app has the next chunk of the body, and may do whatever it wishes with it...
}

NSLog(@"%@",@"Successfully received the entire response body.");