EmailSubscribeViewController to allow users in iOS applications to signup to a MailChimp Email List. This is a companion to my blog post http://kevinvanderlugt.github.io/ios-mailing-list-mailchimp/

EmailSubscribeViewController.h

#import <UIKit/UIKit.h>
@interface EmailSubscribeViewController : UIViewController <UITextFieldDelegate>
@end

EmailSubscribeViewController.m

@interface EmailSubscribeViewController ()

@property (weak, nonatomic) IBOutlet UITextField *emailField;
@property (weak, nonatomic) IBOutlet UITextField *firstNameField;
@property (weak, nonatomic) IBOutlet UITextField *lastNameField;

@end

@implementation EmailSubscribeViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

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

- (IBAction)backPressed:(id)sender {
    [self.navigationController popViewControllerAnimated:YES];
}

- (IBAction)submitPressed:(id)sender {
    // Get all the user inputs, no real validation is done here but you could
    NSString *email = self.emailField.text;
    NSString *firstName = self.firstNameField.text;
    NSString *lastName = self.lastNameField.text;
    
    // The MailChimp API that we are using was version 2.0, this may change
    // API_ZONE should be replaced with your api zone
    // This can be found at the end of your api key, mine was us8
    NSString *urlString = @"https://API_ZONE.api.mailchimp.com/2.0/lists/subscribe";
    NSMutableURLRequest *urlRequest =
        [NSMutableURLRequest requestWithURL:[NSURL URLWithString:urlString]
                                cachePolicy:NSURLRequestUseProtocolCachePolicy
                            timeoutInterval:60.0];
    
    [urlRequest setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [urlRequest setHTTPMethod:@"POST"];
    
    // Create the body using the native json generator
    NSMutableDictionary *body = [[NSMutableDictionary alloc] init];

    // Replace API_KEY with your api key found earlier
    [body setObject:@"API_KEY" forKey:@"apikey"];

    // Replace LIST_ID with your list ID
    [body setObject:@"LIST_ID" forKey:@"id"];

    NSMutableDictionary *emailDictionary = [[NSMutableDictionary alloc] init];
    [emailDictionary setObject:email forKey:@"email"];
    
    [body setObject:emailDictionary forKey:@"email"];
    
    // Merge variables are values passed into your list including user's name
    NSMutableDictionary *mergeVariables = [[NSMutableDictionary alloc] init];
    if(firstName) {
        [mergeVariables setObject:firstName forKey:@"FNAME"];
    }
    if(lastName) {
        [mergeVariables setObject:lastName forKey:@"LNAME"];
    }
    
    [body setObject:mergeVariables forKey:@"merge_vars"];
    
    // Optionally you can disable email verification
    [body setObject:@NO forKey:@"double_optin"];
    
    NSData *requestBody = [NSJSONSerialization dataWithJSONObject:body options:0 error:nil];
    
    [urlRequest setHTTPBody:requestBody];
    
    [NSURLConnection sendAsynchronousRequest:urlRequest
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:^(NSURLResponse *response, NSData *responseData, NSError *error){
                               if (error != nil) {
                                   NSLog(@"Error subscribing to the list: %@", [error localizedDescription]);
                               } else {
                                  // Do something useful here to thank your users
                                  NSLog(@"Success, thanks for signing up!");
                               }
                           }];
}

-(BOOL)textFieldShouldReturn:(UITextField *)textField
{
    [textField resignFirstResponder];
    return YES;
}

@end