UITextField keyboard pop up after api response received - objective-c

Question

In my app am using UITextField in the login screen. To get the login details I connect the app to server through API. While calling the api I display an activity UIActivityIndicatorView. Before calling the api I do end editing. once the response is received from server again the keyboard is pop up when the activity indicator stops
Here is my Code
[self.view endEditing:YES];
VW_overlay.hidden = NO;
[activityIndicatorView startAnimating];
[self performSelector:#selector(API_Login) withObject:activityIndicatorView afterDelay:0.01];
and the API_Login Method have the following code
-(void) API_Login
{
NSString *userEmail = _TXT_email.text;
NSString *userPWD = _TXT_password.text;
NSError *error;
NSHTTPURLResponse *response = nil;
NSString *post = [NSString stringWithFormat:#"username=%#&password=%#",userEmail,userPWD];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
NSString *postLength = [NSString stringWithFormat:#"%lu",(unsigned long)[postData length]];
NSString *urlGetuser =[NSString stringWithFormat:#"%#loginApi",SERVER_URL];
NSURL *urlProducts=[NSURL URLWithString:urlGetuser];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:urlProducts];
[request setHTTPMethod:#"POST"];
[request setValue:postLength forHTTPHeaderField:#"Content-Length"];
[request setValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Content-Type"];
[request setHTTPBody:postData];
[request setHTTPShouldHandleCookies:NO];
NSData *aData = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
if (aData)
{
NSMutableDictionary *json_DATA = (NSMutableDictionary *)[NSJSONSerialization JSONObjectWithData:aData options:NSASCIIStringEncoding error:&error];
NSLog(#"The response %#",json_DATA);
if ([[json_DATA valueForKey:#"status"]isEqualToString:#"success"]) {
[[NSUserDefaults standardUserDefaults] setValue:[json_DATA valueForKey:#"driver_id"] forKey:#"driver_id"];
[[NSUserDefaults standardUserDefaults] synchronize];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[json_DATA valueForKey:#"status"] message:[json_DATA valueForKey:#"msg"] delegate:self cancelButtonTitle:nil otherButtonTitles:#"Ok", nil];
[alert show];
[activityIndicatorView stopAnimating];
VW_overlay.hidden = YES;
[self performSelector:#selector(stop_activity) withObject:nil afterDelay:1.0];
}
else
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:[json_DATA valueForKey:#"status"] message:[json_DATA valueForKey:#"msg"] delegate:self cancelButtonTitle:nil otherButtonTitles:#"Ok", nil];
[alert show];
}
}
else
{
[activityIndicatorView stopAnimating];
VW_overlay.hidden = YES;
NSLog(#"Error %#\nResponse %#",error,response);
}
}
-(void) stop_activity
{
[self order_details_page];
}
-(void)order_details_page
{
[self performSegueWithIdentifier:#"login_order" sender:self];
}