(Objective-C) Google Drive Refresh Access Token

Demonstrates how to automatically refresh the access token when it expires.

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

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

BOOL success = YES;

// This example uses a previously obtained access token having permission for the 
// Google Drive scope.

// The access token (and refresh token) was previously saved to a JSON file with this format:
// See Get Google Drive OAuth2 Access Token

// {
//   "access_token": "ya29.Gls-BsdxTWuenChv ... yzVIrXikkLxu5T6dy4I6GjADFardoz4Lruw",
//   "expires_in": 3600,
//   "refresh_token": "1/tMBJ ... 27D-Hk6rpQYBA",
//   "scope": "https://www.googleapis.com/auth/drive",
//   "token_type": "Bearer"
// }

CkoJsonObject *json = [[CkoJsonObject alloc] init];
NSString *tokenFilePath = @"qa_data/tokens/googleDrive.json";
[json LoadFile: tokenFilePath];

CkoOAuth2 *oauth2 = [[CkoOAuth2 alloc] init];
oauth2.AccessToken = [json StringOf: @"access_token"];
oauth2.RefreshToken = [json StringOf: @"refresh_token"];

oauth2.AuthorizationEndpoint = @"https://accounts.google.com/o/oauth2/v2/auth";
oauth2.TokenEndpoint = @"https://www.googleapis.com/oauth2/v4/token";

//  Replace these with actual values.
oauth2.ClientId = @"GOOGLE-CLIENT-ID";
oauth2.ClientSecret = @"GOOGLE-CLIENT-SECRET";
oauth2.Scope = @"https://www.googleapis.com/auth/drive";

// Use OAuth2 to refresh the access token.
success = [oauth2 RefreshAccessToken];
if (success != YES) {
    NSLog(@"%@",oauth2.LastErrorText);
    return;
}

NSLog(@"%@",oauth2.AccessTokenResponse);

// Save the new access token to our JSON file (so we can refresh it again when needed).
[json UpdateString: @"access_token" value: oauth2.AccessToken];

CkoFileAccess *fac = [[CkoFileAccess alloc] init];
[fac WriteEntireTextFile: tokenFilePath fileData: [json Emit] charset: @"utf-8" includePreamble: NO];

NSLog(@"%@",@"Access Token Refreshed!");