The following code will show the Alert with textField :-

UIAlertController *alert=[UIAlertController alertControllerWithTitle:@"Alert Title" message:nil preferredStyle:UIAlertControllerStyleAlert];
    
    // to add textField
    
[alert addTextFieldWithConfigurationHandler:^(UITextField *textField){
        
    //  do any textField related code here
        
 }];

We need to dismiss the alert also.. So for that we will add a action to the UIAlert to dismiss it.. Here, its shows two buttons OK and CANCEL added to the UIAlert.. The code is :-

UIAlertAction *updateAction=[UIAlertAction actionWithTitle:@"Ok" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
  
        UITextField *txtField = [alert.textFields firstObject];
        NSLog(@"Your text %@",txtField.text);  // to access the text field value
        
    }];
    
UIAlertAction *dismissAction=[UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction  *_Nonnull action) {
        
    }];
    
    [alert addAction:updateAction];
    [alert addAction:dismissAction];

Its working !!