NewViewController.m

//
//  NewViewController.m
//  AlertButton
//
//  Created by Rafat Touqir Rafsun on 2/14/19.
//

#import "NewViewController.h"


//IMPORT The RKDropdownAlert here in your viewcontroller
#import <RKDropdownAlert/RKDropdownAlert.h>




@interface NewViewController ()

@end

@implementation NewViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
}

- (void)viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];
    
    //call the alert function here
    [self showDropDownAlert];
    
    
}


- (void) showDropDownAlert{
    [RKDropdownAlert title:@"HI" message:@"HEllo"];
}



@end

Podfile

# Uncomment the next line to define a global platform for your project
platform :ios, '11.0'

target 'AlertButton' do
  # Comment the next line if you're not using Swift and don't want to use dynamic frameworks
  use_frameworks!

  # Pods for AlertButton
pod 'RKDropdownAlert' #new alert library for objc-c viewcontroller

end