MFMailComposeViewController

ViewController.m

// At top of ViewController implementation
#import <MessageUI/MessageUI.h>
#import <MessageUI/MFMailComposeViewController.h>

@interface ViewController () <MFMailComposeViewControllerDelegate>
@end

@implementation ViewController

- (void)sendEmail {
    MFMailComposeViewController *vc = [[MFMailComposeViewController alloc] init];
    vc.mailComposeDelegate = self;
    
    // 1. Set Subject from template, personalized with Branch link & first name
    NSString *firstName = [self.nameTextField.text componentsSeparatedByString:@" "][0];
    [vc setSubject:[NSString stringWithFormat:self.currentTemplate[@"subject"], firstName]];
    
    // 2. Set message from template
    [vc setMessageBody:[self getMessageBodyWithFirstName:firstName
                                                     url:self.url
                                                template:self.currentTemplate[@"body"]]];
    
    // 3. Set recipient
    [vc setToRecipients:[NSMutableArray arrayWithObject:self.emailAddressTextField.text]];
    
    // 4. Pull up screen with email, ready to send!
    [self presentViewController:vc animated:YES completion:nil];
}

- (void)mailComposeController:(MFMailComposeViewController*)controller
          didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error
{
    [controller dismissViewControllerAnimated:YES completion:nil];
}