邮件功能无法发送到iOS中的收件人

Question

我用xcode创建了邮件发送功能。

- (void)onShareBtn:(UIButton *)button
{
    MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init];
    picker.mailComposeDelegate = self;

    [picker setSubject:@"Hello!"];

    // Set up the recipients.
    NSArray *toRecipients = [NSArray arrayWithObjects:@"first@gmail.com",
                             nil];
    NSArray *ccRecipients = [NSArray arrayWithObjects:@"second@gmail.com",
                             nil];
    NSArray *bccRecipients = [NSArray arrayWithObjects:@"third@gmail.com",
                              nil];

    [picker setToRecipients:toRecipients];
    [picker setCcRecipients:ccRecipients];
    [picker setBccRecipients:bccRecipients];
    [picker setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];

    // Attach an image to the email.
    NSString *path = [[NSBundle mainBundle] pathForResource:@"share"
                                                     ofType:@"png"];
    NSData *myData = [NSData dataWithContentsOfFile:path];
    [picker addAttachmentData:myData mimeType:@"image/png"
                     fileName:@"share"];

    // Fill out the email body text.
    NSString *emailBody = @"It is raining!";
    [picker setMessageBody:emailBody isHTML:NO];

    // Present the mail composition interface.
    [self presentModalViewController:picker animated:YES];
}

- (void) mailComposeController:(MFMailComposeViewController *)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError *)error
{
    if(error)
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"error" message:[NSString stringWithFormat:@"error %@",[error description]] delegate:nil cancelButtonTitle:@"dismiss" otherButtonTitles:nil, nil];
        [alert show];
        [self dismissViewControllerAnimated:YES completion:NULL];
    }
    else
    {
        switch (result)
        {
            case MFMailComposeResultCancelled:
                NSLog(@"Mail cancelled");
                break;
            case MFMailComposeResultSaved:
                NSLog(@"Mail saved");
                break;
            case MFMailComposeResultSent:
                NSLog(@"Mail sent");
                break;
            case MFMailComposeResultFailed:
                NSLog(@"Mail sent failure: %@", [error localizedDescription]);
                break;
            default:
                break;
        }

        // Close the Mail Interface
        [self dismissViewControllerAnimated:YES completion:NULL];
    }
}

此代码只能显示邮件表单，当我点击发送按钮时，它无法正确地将邮件发送给收件人。 此功能仅显示发送邮件表单。 如何为正确发送给收件人的邮件更新此代码？