(Objective-C) REST Follow Redirects

Demonstrates how to follow a 302/303 redirect response.

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#import <CkoRest.h>
#import <NSString.h>
#import <CkoUrl.h>

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

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

BOOL bTls = YES;
int port = 443;
BOOL bAutoReconnect = YES;
BOOL success = [rest Connect: @"chilkatsoft.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// Send a POST to a URL that will respond with a 302 redirect..
[rest AddQueryParam: @"firstName" value: @"John"];
[rest AddQueryParam: @"lastName" value: @"Doe"];
NSString *responseText = [rest FullRequestFormUrlEncoded: @"POST" uriPath: @"/echoPost302.asp"];
if (rest.LastMethodSuccess != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

int statusCode = [rest.ResponseStatusCode intValue];

// Examine the response status code
if (statusCode < 300) {
    NSLog(@"%@",@"Not a redirect.");
    NSLog(@"%@",responseText);
    return;
}

if (statusCode > 399) {
    NSLog(@"%@%d",@"Error response: Status code = ",statusCode);
    NSLog(@"%@",responseText);
    return;
}

NSLog(@"%@%d",@"Redirect status code = ",statusCode);

// The response header will contain a Location field with the redirect URL, such as this:
// Location: http://www.chilkatsoft.com/echoPostFinal.asp

// The response status code determines how the client should behave.
// Here are some common possibilities:

// 301: Moved Permanently
// This and all future requests should be directed to the given URI.  (Keep the original HTTP method for the redirect.  In this case, the 
// original request was a POST, so we POST to the redirect URL.)

// 302: Found (aka Object Moved aka Moved Temporarily)
// This is the most popular redirect code, but also an example of industrial practice contradicting the standard. HTTP/1.0 specification (RFC 1945 ) required the client
// to perform a temporary redirect (the original describing phrase was Moved Temporarily), but popular browsers implemented it as a 303 See Other. Therefore, HTTP/1.1
// added status codes 303 and 307 to disambiguate between the two behaviors. However, the majority of Web applications and frameworks still use the 302 status code
// as if it were the 303.

// 303: See Other
// The response to the request can be found under another URI using a GET method. When received in response to a PUT, it should be assumed that the server has
// received the data and the redirect should be issued with a separate GET message.

// 307: Temporary Redirect
// In this occasion, the request should be repeated with another URI, but future requests can still use the original URI. In contrast to 303, the request method
// should not be changed when reissuing the original request. For instance, a POST request must be repeated using another POST request.

NSLog(@"%@",rest.ResponseHeader);

CkoUrl *redirectUrl = [rest RedirectUrl];
if (rest.LastMethodSuccess == NO) {
    NSLog(@"%@",@"No Location header found for redirect.");
    return;
}

// Prep for the redirect..
[rest ClearAllParts];

// Disconnect and re-connect.  
// (This can be skipped if both the host and SSL/TLS conditions are the same.)
[rest Disconnect: [NSNumber numberWithInt: 100]];
success = [rest Connect: redirectUrl.Host port: redirectUrl.Port tls: redirectUrl.Ssl autoReconnect: bAutoReconnect];
if (success != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

if ((statusCode == 301) || (statusCode == 307)) {
    // Redirect using a POST, sending the same params to the new destination
    [rest AddQueryParam: @"firstName" value: @"John"];
    [rest AddQueryParam: @"lastName" value: @"Doe"];
    responseText = [rest FullRequestFormUrlEncoded: @"POST" uriPath: redirectUrl.Path];
    if (rest.LastMethodSuccess != YES) {
        NSLog(@"%@",rest.LastErrorText);
        return;
    }

}

if ((statusCode == 302) || (statusCode == 303)) {
    // Redirect using a GET, sending the query params found in the redirect URL.
    responseText = [rest FullRequestFormUrlEncoded: @"GET" uriPath: redirectUrl.PathWithQueryParams];
    if (rest.LastMethodSuccess != YES) {
        NSLog(@"%@",rest.LastErrorText);
        return;
    }

}

// Show the final status code and the response text.
NSLog(@"%@%d",@"Final status code = ",[rest.ResponseStatusCode intValue]);

NSLog(@"%@",@"Final response text (HTML, XML, JSON, or whatever..)");
NSLog(@"%@",responseText);