ios - Amazon SES: sending email error -

i using awsses sending email.

- (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions {     awsstaticcredentialsprovider *credentialsprovider = [[awsstaticcredentialsprovider alloc] initwithaccesskey:my_key secretkey:my_secret];      awsserviceconfiguration *configuration = [[awsserviceconfiguration alloc] initwithregion:awsregionuseast1                                                                                                                                              credentialsprovider:credentialsprovider];     [awslogger defaultlogger].loglevel = awslogleveldebug;      [awsses registerseswithconfiguration:configuration forkey:@"useast1ses"];  } 

send email function

- (void) email {      awssescontent *messagebody = [[awssescontent alloc] init];     messagebody.data = [nsstring stringwithformat: @"test email"];       awssescontent *subject = [[awssescontent alloc] init];     subject.data = [nsstring stringwithformat: @"feedback user"];       awssesbody *body = [[awssesbody alloc] init];     body.text = messagebody;       awssesmessage *message = [[awssesmessage alloc] init];     message.subject = subject;     message.body    = body;       awssesdestination *destination = [[awssesdestination alloc] init];     destination.toaddresses =  @[email_verified];       awssessendemailrequest *ser = [[awssessendemailrequest alloc] init];     ser.source      = email_verified;     ser.destination = destination;     ser.message     = message;       awsses *ses = [awsses sesforkey:@"useast1ses"];     [ses sendemail:ser completionhandler:^(awssessendemailresponse * _nullable response, nserror * _nullable error) {          nslog(@" email");     }];  } 

i getting following error

error domain=com.amazonaws.awsserviceerrordomain code=3 "(null)" userinfo={type=sender, message=the request signature calculated not match signature provided. check aws secret access key , signing method. consult service documentation details.  canonical string request should have been 'post /  content-type:application/x-www-form-urlencoded; charset=utf-8 host:email.us-east-1.amazonaws.com user-agent:aws-sdk-ios/2.4.0 iphone-os/9.2 en_us x-amz-date:20160425t063758z  content-type;host;user-agent;x-amz-date 16cb4baebd2874efba56f725430b36a57d5efa17b3af5d9fc38856fa0f17d5e5'  string-to-sign should have been 'aws4-hmac-sha256 20160425t063758z 20160425/us-east-1/email/aws4_request 9d3d181a3ab229898db9d7578b7b485ad61c19e07fe14c38d35ee4ed38ef1a94' , code=signaturedoesnotmatch, __text=(     "\n    ",     "\n    ",     "\n    ",     "\n  " )} 

i have been struggling error more day. appreciated. couldn't find proper documentation this.

note: able configure awsses in server same email , secret key