Objective-C

OAuth2 Token using IdentityServer4 with Client Credentials

See more OAuth2 Examples

Demonstrates how to get an OAuth2 access token using the client credential flow with IdentityServer4. Objective-C

#import <CkoHttp.h>
#import <CkoHttpResponse.h>
#import <CkoJsonObject.h>
#import <NSString.h>
#import <CkoJsonArray.h>
#import <CkoHttpRequest.h>

BOOL success = NO;

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

CkoHttp *http = [[CkoHttp alloc] init];

//  The first step is to fetch your IdentityServer4's discovery document
//  (OpenID Connect defines a discovery mechanism, called OpenID Connect Discovery, where an OpenID server publishes its metadata at a well-known URL, 
//  typically https://server.com/.well-known/openid-configuration

CkoHttpResponse *resp = [[CkoHttpResponse alloc] init];
success = [http HttpNoBody: @"GET" url: @"https://localhost:5000/.well-known/openid-configuration" response: resp];
if (success == NO) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

if ([resp.StatusCode intValue] != 200) {
    NSLog(@"%@%d",@"Received response status code ",[resp.StatusCode intValue]);
    NSLog(@"%@",@"Response body containing error text or JSON:");
    NSLog(@"%@",resp.BodyStr);
    return;
}

CkoJsonObject *json = [[CkoJsonObject alloc] init];
success = [json Load: resp.BodyStr];

//  We have the discovery document, which contains something like this:

//  You can use this online tool to generate parsing code from sample JSON: 
//  Generate Parsing Code from JSON

//  {
//    "issuer": "https://localhost:5000",
//    "jwks_uri": "https://localhost:5000/.well-known/openid-configuration/jwks",
//    "authorization_endpoint": "https://localhost:5000/connect/authorize",
//    "token_endpoint": "https://localhost:5000/connect/token",
//    "userinfo_endpoint": "https://localhost:5000/connect/userinfo",
//    "end_session_endpoint": "https://localhost:5000/connect/endsession",
//    "check_session_iframe": "https://localhost:5000/connect/checksession",
//    "revocation_endpoint": "https://localhost:5000/connect/revocation",
//    "introspection_endpoint": "https://localhost:5000/connect/introspect",
//    "frontchannel_logout_supported": true,
//    "frontchannel_logout_session_supported": true,
//    "backchannel_logout_supported": true,
//    "backchannel_logout_session_supported": true,
//    "scopes_supported": [
//      "openid",
//      "profile",
//      "email",
//      "MyCompany.profile",
//      "MyCompany.Identity.WebApi",
//      "MyCompany.TriHub.WebApi",
//      "offline_access"
//    ],
//    "claims_supported": [
//      "sub",
//      "updated_at",
//      "locale",
//      "zoneinfo",
//      "birthdate",
//      "gender",
//      "website",
//      "profile",
//      "preferred_username",
//      "nickname",
//      "middle_name",
//      "given_name",
//      "family_name",
//      "name",
//      "picture",
//      "email_verified",
//      "email",
//      "userId",
//      "groups",
//      "fullname"
//    ],
//    "grant_types_supported": [
//      "authorization_code",
//      "client_credentials",
//      "refresh_token",
//      "implicit",
//      "password"
//    ],
//    "response_types_supported": [
//      "code",
//      "token",
//      "id_token",
//      "id_token token",
//      "code id_token",
//      "code token",
//      "code id_token token"
//    ],
//    "response_modes_supported": [
//      "form_post",
//      "query",
//      "fragment"
//    ],
//    "token_endpoint_auth_methods_supported": [
//      "client_secret_basic",
//      "client_secret_post"
//    ],
//    "subject_types_supported": [
//      "public"
//    ],
//    "id_token_signing_alg_values_supported": [
//      "RS256"
//    ],
//    "code_challenge_methods_supported": [
//      "plain",
//      "S256"
//    ]
//  }
//  

//  The next steps are to (1) get the token_endpoint,
//  and (2) verify that the client_credentials grant type is supported.

NSString *tokenEndpoint = [json StringOf: @"token_endpoint"];

CkoJsonArray *grantTypes = [json ArrayOf: @"grant_types_supported"];
int clientCredentialsIdx = [[grantTypes FindString: @"client_credentials" caseSensitive: YES] intValue];

//  If clientCredentialsIdx is less then zero (-1) then the "client_credentials" string was not found.
if (clientCredentialsIdx < 0) {
    NSLog(@"%@",@"The client credentials grant type is not supported.");
    return;
}

//  Request the access token using our Client ID and Client Secret.
//  We're going to duplicate this CURL statement:

//  curl --request POST \
//    --url '<tokenEndpoint>' \
//    --header 'content-type: application/x-www-form-urlencoded' \
//    --data 'grant_type=client_credentials&client_id=CLIENT_ID&client_secret=CLIENT_SECRET'

CkoHttpRequest *req = [[CkoHttpRequest alloc] init];
req.HttpVerb = @"POST";
req.ContentType = @"application/x-www-form-urlencoded";

[req AddParam: @"grant_type" value: @"client_credentials"];
[req AddParam: @"client_id" value: @"CLIENT_ID"];
[req AddParam: @"client_secret" value: @"CLIENT_SECRET"];req.HttpVerb = @"POST";

success = [http HttpReq: tokenEndpoint request: req response: resp];
if (success == NO) {
    NSLog(@"%@",http.LastErrorText);
    return;
}

//  Make sure we got a 200 response status code, otherwise it's an error.
if ([resp.StatusCode intValue] != 200) {
    NSLog(@"%@",@"POST to token endpoint failed.");
    NSLog(@"%@%d",@"Received response status code ",[resp.StatusCode intValue]);
    NSLog(@"%@",@"Response body containing error text or JSON:");
    NSLog(@"%@",resp.BodyStr);
    return;
}

success = [json Load: resp.BodyStr];

//  Our JSON response should contain this:
//  {
//    "access_token":"eyJz93a...k4laUWw",
//    "token_type":"Bearer",
//    "expires_in":86400
//  }

//  Get the access token:
NSString *accessToken = [json StringOf: @"access_token"];

//  The access token is what gets added to "Authorization: Bearer <access_token>"
//  for the subsequent REST API calls..