Objective-C

HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to get an HMRC OAuth2 access token from a desktop (installed) application or script. This example gets an HMRC MTD VAT read/write access token. Objective-C

#import <CkoOAuth2.h>
#import <NSString.h>
#import <CkoJsonObject.h>
#import <CkoDateTime.h>
#import <CkoFileAccess.h>

BOOL success = NO;

//  To further clarify, see OAuth 2.0 Authorization Flow

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

//  This should be the port in the localhost callback URL for your app.
//  Important: Make sure the callback URI in your HMRC developer app 
//  is exactly "http://localhost:3017/".  Don't forget the ending "/" char.
//  The callback URL would look like "http://localhost:3017/" if the port number is 3017.

//  IMPORTANT: Don't forget to setup your HMRC application to use the Redirect URI "http://localhost:3017/" as shown
//  here: Configure Redirect URI for HMRC application
oauth2.ListenPort = [NSNumber numberWithInt:3017];

oauth2.AuthorizationEndpoint = @"https://test-api.service.hmrc.gov.uk/oauth/authorize";
oauth2.TokenEndpoint = @"https://test-api.service.hmrc.gov.uk/oauth/token";

//  Replace with your actual client ID
oauth2.ClientId = @"HMRC-CLIENT-ID";

//  The scopes are documented in the HMRC reference documentation for each API.
//  This example gets a read/write access token for the HMRC MTD VAT API.
oauth2.Scope = @"read:vat write:vat";

//  Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
NSString *url = [oauth2 StartAuth];
if (oauth2.LastMethodSuccess != YES) {
    NSLog(@"%@",oauth2.LastErrorText);
    return;
}

//  Launch the default browser on the system and navigate to the url.
//  The LaunchBrowser method was added in Chilkat v10.1.2.
success = [oauth2 LaunchBrowser: url];
if (success == NO) {
    NSLog(@"%@",oauth2.LastErrorText);
    return;
}

//  Wait for the user to approve or deny authorization in the browser.
int numMsWaited = 0;
while ((numMsWaited < 90000) && ([oauth2.AuthFlowState intValue] < 3)) {
    [oauth2 SleepMs: [NSNumber numberWithInt: 100]];
    numMsWaited = numMsWaited + 100;
}

//  If the browser does not respond within the specified time, AuthFlowState will be:
//  
//  1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
//  2: Waiting for Final Response – The thread is awaiting the final access token response.
//  In either case, cancel the background task initiated by StartAuth.

if ([oauth2.AuthFlowState intValue] < 3) {
    [oauth2 Cancel];
    NSLog(@"%@",@"No response from the browser!");
    return;
}

//  Check AuthFlowState to determine if authorization was granted, denied, or failed:
//  
//  3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
//  4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
//  5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

if ([oauth2.AuthFlowState intValue] == 5) {
    NSLog(@"%@",@"OAuth2 failed to complete.");
    NSLog(@"%@",oauth2.FailureInfo);
    return;
}

if ([oauth2.AuthFlowState intValue] == 4) {
    NSLog(@"%@",@"OAuth2 authorization was denied.");
    NSLog(@"%@",oauth2.AccessTokenResponse);
    return;
}

if ([oauth2.AuthFlowState intValue] != 3) {
    NSLog(@"%@%d",@"Unexpected AuthFlowState:",[oauth2.AuthFlowState intValue]);
    return;
}

NSLog(@"%@",@"OAuth2 authorization granted!");
NSLog(@"%@%@",@"Access Token = ",oauth2.AccessToken);

//  Get the full JSON response:
CkoJsonObject *json = [[CkoJsonObject alloc] init];
[json Load: oauth2.AccessTokenResponse];
json.EmitCompact = NO;
NSLog(@"%@",[json Emit]);

//  The JSON response looks like this:

//  {
//    "token_type": "Bearer",
//    "scope": "user_impersonation",
//    "expires_in": "3599",
//    "ext_expires_in": "0",
//    "expires_on": "1524783438",
//    "not_before": "1524779538",
//    "resource": "https://mydomain.api.crm.dynamics.com",
//    "access_token": "...",
//    "refresh_token": "...",
//    "id_token": "..."
//  }

//  If an "expires_on" member does not exist, then add the JSON member by
//  getting the current system date/time and adding the "expires_in" seconds.
//  This way we'll know when the token expires.
if ([json HasMember: @"expires_on"] != YES) {
    CkoDateTime *dtExpire = [[CkoDateTime alloc] init];
    [dtExpire SetFromCurrentSystemTime];
    [dtExpire AddSeconds: [json IntOf: @"expires_in"]];
    [json AppendString: @"expires_on" value: [dtExpire GetAsUnixTimeStr: NO]];
}

NSLog(@"%@",[json Emit]);

//  Save the JSON to a file for future requests.
CkoFileAccess *fac = [[CkoFileAccess alloc] init];
[fac WriteEntireTextFile: @"qa_data/tokens/hmrc.json" fileData: [json Emit] charset: @"utf-8" includePreamble: NO];