Objective-c – When will [MFMailComposeViewController canSendMail] return NO

1. You will only need a ScrollView if the contents you have now do not fit in the iPhone screen. (If you are adding the ScrollView as the superview of the components just to make the TextField scroll up when keyboard comes up, then it's not needed.)

2. The standard way to prevent the TextFields from being covered by the keyboard is to move the view up/down whenever the keyboard is shown.

Here is some sample code:

#define kOFFSET_FOR_KEYBOARD 80.0

-(void)keyboardWillShow {
    // Animate the current view out of the way
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)keyboardWillHide {
    if (self.view.frame.origin.y >= 0)
    {
        [self setViewMovedUp:YES];
    }
    else if (self.view.frame.origin.y < 0)
    {
        [self setViewMovedUp:NO];
    }
}

-(void)textFieldDidBeginEditing:(UITextField *)sender
{
    if ([sender isEqual:mailTf])
    {
        //move the main view, so that the keyboard does not hide it.
        if  (self.view.frame.origin.y >= 0)
        {
            [self setViewMovedUp:YES];
        }
    }
}

//method to move the view up/down whenever the keyboard is shown/dismissed
-(void)setViewMovedUp:(BOOL)movedUp
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:0.3]; // if you want to slide up the view

    CGRect rect = self.view.frame;
    if (movedUp)
    {
        // 1. move the view's origin up so that the text field that will be hidden come above the keyboard 
        // 2. increase the size of the view so that the area behind the keyboard is covered up.
        rect.origin.y -= kOFFSET_FOR_KEYBOARD;
        rect.size.height += kOFFSET_FOR_KEYBOARD;
    }
    else
    {
        // revert back to the normal state.
        rect.origin.y += kOFFSET_FOR_KEYBOARD;
        rect.size.height -= kOFFSET_FOR_KEYBOARD;
    }
    self.view.frame = rect;

    [UIView commitAnimations];
}


- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    // register for keyboard notifications
    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillShow)
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(keyboardWillHide)
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    // unregister for keyboard notifications while not visible.
    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillShowNotification
                                           object:nil];

    [[NSNotificationCenter defaultCenter] removeObserver:self
                                             name:UIKeyboardWillHideNotification
                                           object:nil];
}

Use this code this will definitely work:

    -(IBAction)send{

        [self callMailComposer];
    }

    -(void)callMailComposer{

        Class mailClass = (NSClassFromString(@"MFMailComposeViewController"));
        if (mailClass != nil)
        {
        // We must always check whether the current device is configured for sending emails
            if ([mailClass canSendMail])
                [self displayComposerSheet];
            else
                [self launchMailAppOnDevice];
        }

        else
        {
            [self launchMailAppOnDevice];
        }
    }


    #pragma mark -
    #pragma mark Compose Mail
    #pragma mark 

    // Displays an email composition interface inside the application. Populates all the Mail fields. 
    -(void)displayComposerSheet{

        MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init];


        picker.mailComposeDelegate = self;
        NSString *tosubject =@"";
        [picker setSubject:tosubject];


        // Set up recipients
        [picker setCcRecipients:nil];   
        [picker setBccRecipients:nil];

        [picker setToRecipients:nil];



        [picker setMessageBody:strNewsLink isHTML:NO];

        [self presentModalViewController:picker animated:YES];

        if(picker) [picker release];
        if(picker) picker=nil;

    }


    // Dismisses the email composition interface when users tap Cancel or Send. Proceeds to update the message field with the result of the operation.

        - (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error
{    
  NSString* alertMessage;
  // message.hidden = NO;
  // Notifies users about errors associated with the interface
  switch (result)
  {
    case MFMailComposeResultCancelled:
      alertMessage = @"Email composition cancelled";
      break;
    case MFMailComposeResultSaved:
      alertMessage = @"Your e-mail has been saved successfully";

      break;
    case MFMailComposeResultSent:
      alertMessage = @"Your email has been sent successfully";

      break;
    case MFMailComposeResultFailed:
      alertMessage = @"Failed to send email";

      break;
    default:
      alertMessage = @"Email Not Sent";

      break;
  }

  UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:@"My app name" 
                                                      message:alertMessage
                                                     delegate:nil
                                            cancelButtonTitle:@"OK"
                                            otherButtonTitles:nil];
  [alertView show];
  [self dismissModalViewControllerAnimated:YES];
}


    #pragma mark 
    #pragma mark Workaround
    #pragma mark
    // Launches the Mail application on the device.

        -(void)launchMailAppOnDevice{

        NSString *recipients = @"mailto:?cc=&subject=";
        NSString *body = @"&body=";
        NSString *email = [NSString stringWithFormat:@"%@%@", recipients, body];
        email = [email stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:email]];

    }