Objective-C

Refresh OAuth2 Access Token with Optional Params

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Demonstrates how to refresh an OAuth2 access token with optional query params included in the HTTP request. Objective-C

#import <CkoJsonObject.h>
#import <CkoOAuth2.h>
#import <CkoStringBuilder.h>

BOOL success = NO;

//  Here is a sampling of possible optional parameters that might
//  be used by some OAuth2 providers.

//  Optional Parameters
//  
//      "scope":
//          Specifies the scope of the access request. If omitted, the authorization
//          server may issue a token with the same scope as the original token.
//          Example: "scope=read write"
//  
//      "redirect_uri":
//          The redirect URI used in the original authorization request. Some
//          servers may require this for validation.
//          Example: "redirect_uri=https://example.com/callback"
//  
//      "resource":
//          Indicates the target resource or audience for the token. This is used in
//          some implementations (e.g., Microsoft Identity Platform).
//          Example: "resource=https://api.example.com"
//  
//      "audience":
//          Similar to "resource", this specifies the intended audience for the
//          token (used in some OAuth2 implementations like Auth0).
//          Example: "audience=https://api.example.com"
//  
//      "client_assertion" and "client_assertion_type":
//          Used for client authentication using a signed JWT instead of a client
//          secret.
//          Example:client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9...        
//          client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer
//  
//      "token_type_hint":
//          Provides a hint to the authorization server about the type of token
//          being refreshed. This is rarely used but can be helpful in some cases.
//          Example: "token_type_hint=refresh_token"
//  
//      "assertion":
//          Used in some flows (e.g., SAML bearer assertion flow) to provide an
//          assertion for token issuance.
//          Example: "assertion=PHNhbWxwOl..."
//  
//      "requested_token_use":
//          Specifies how the token will be used (e.g., "on_behalf_of" in the
//          On-Behalf-Of flow used by Microsoft Identity Platform).
//          Example: "requested_token_use=on_behalf_of"
//  

//  --------------------------------------------------------------------------------
//  This example wll refresh the access token and includes the "audience"
//  optional query parameter.
//  
//  

//  Get the access token to be refreshed.
CkoJsonObject *jsonToken = [[CkoJsonObject alloc] init];
success = [jsonToken LoadFile: @"qa_data/tokens/myAccessToken.json"];
if (success != YES) {
    NSLog(@"%@",@"Failed to load hmrc.json");
    return;
}

CkoOAuth2 *oauth2 = [[CkoOAuth2 alloc] init];

oauth2.TokenEndpoint = @"https://api.example.com/oauth/token";

//  Replace these with actual values.
oauth2.ClientId = @"CLIENT_ID";
oauth2.ClientSecret = @"CLIENT_SECRET";

//  Add the optional refresh query param.
//  Call AddRefreshQueryParam multiple times to add additional params.
[oauth2 AddRefreshQueryParam: @"audience" value: @"https://api.example.com"];

//  Provide the existing refresh token from the JSON.
oauth2.RefreshToken = [jsonToken StringOf: @"refresh_token"];

//  Send the HTTP POST to refresh the access token..
success = [oauth2 RefreshAccessToken];
if (success != YES) {
    NSLog(@"%@",oauth2.LastErrorText);
    return;
}

//  Load the access token response into the json object 
[jsonToken Load: oauth2.AccessTokenResponse];

//  Save the new JSON access token response to a file.
//  The access + refresh tokens contained in this JSON will be needed for the next refresh.
CkoStringBuilder *sbJson = [[CkoStringBuilder alloc] init];
jsonToken.EmitCompact = NO;
[jsonToken EmitSb: sbJson];
[sbJson WriteFile: @"qa_data/tokens/myAccessToken.json" charset: @"utf-8" emitBom: NO];

NSLog(@"%@",@"OAuth2 access token refreshed!");
NSLog(@"%@%@",@"New Access Token = ",oauth2.AccessToken);