MFMailComposeViewController 在生产中不起作用

Question

关于为什么MFMailComposeViewController在开发中工作的任何想法，但是当我将Cloudkit环境设置为生产环境时，视图控制器甚至不会弹出？这看起来很奇怪，但我相信是有原因的。5分钟前有效的代码如下。应用程序的其余部分可以工作，并与服务器完美连接。

CKDatabase *publicDatabase = [[CKContainer defaultContainer] publicCloudDatabase];
CKRecordID *record = [[CKRecordID alloc] initWithRecordName:@"hidden for stackoverflow"];
[publicDatabase fetchRecordWithID:record completionHandler:^(CKRecord * record, NSError *error) {
    if (!error) {
        dispatch_async (dispatch_get_main_queue(), ^{
            feedbackNumber = record[@"RequestNumber"];
            NSString* number = record[@"RequestNumber"];
            int value = [number intValue] +1;
            record[@"RequestNumber"] = [NSString stringWithFormat:@"%d",value];
            [publicDatabase saveRecord:record completionHandler:^(CKRecord *savedRecord, NSError *saveError) {
                dispatch_sync(dispatch_get_main_queue(), ^{
                  NSString *emailTitle = [NSString stringWithFormat:@"%@%@%@", @"Request #", [NSString stringWithFormat:@"%d",value], @" - AssassinsX Immerse"];
                  NSString *messageBody = @"Please type your email below";
                  NSArray *toRecipents = [NSArray arrayWithObject:@"email here, hidden for stackoverflow"];
                  MFMailComposeViewController *mc = [[MFMailComposeViewController alloc] init];
                   mc.mailComposeDelegate = self;
                  [mc setSubject:emailTitle];
                  [mc setMessageBody:messageBody isHTML:NO];
                  [mc setToRecipients:toRecipents];
                   [self presentViewController:mc animated:YES completion:nil];
                });
            }];
        });
    }
}];

Answer 1

确保您在设备中添加了任何邮件帐户。这是 Swift 中的代码

import UIKit
import MessageUI
class ViewController: UIViewController,MFMailComposeViewControllerDelegate
{
   override func viewDidLoad() 
   {
      super.viewDidLoad()
      self.SendMail()
   }
   func SendMail()
   {
      let to = ["[e-mail]"]
      let Subject = "Subject Here"
      let MessageBody = "Message Body"            
      let mc: MFMailComposeViewController = MFMailComposeViewController()
      mc.mailComposeDelegate = self
      mc.setSubject(Subject)
      mc.setMessageBody(MessageBody, isHTML: false)
      mc.setToRecipients(to)
      self.presentViewController(mc, animated: true, completion: nil)
   }
}