MFMailComposeViewController仅在第二次点击后出现

Question

我想从模态视图控制器中呈现MFMailComposeViewController 。 基本上，此方法有效，但不能可靠地起作用：

-(void)sendMailTapped:(id)sender{

    [self resetButtonsStateAfterTapping:sender];
    [self dismissPopover];

    if (filesize>10) {
        [self showAlertForExceededMaximumAttachmentSize];
        return;
    }

    @try {
        MFMailComposeViewController *picker = 
                                  [[MFMailComposeViewController alloc] init];
        if ([MFMailComposeViewController canSendMail]) {
            picker.mailComposeDelegate = self;
            NSURL *path =[NSURL urlWithPath:[pageInfoDict valueForKey:@"file_name"] 
                                      docId:[pageInfoDict valueForKey:@"id_doc"]
                                  encrypted:[[pageInfoDict valueForKey:@"encrypted"] 
                                                                         boolValue]] ;
            NSString *fileName = [pageInfoDict valueForKey:@"title"];
            if([fileName length] == 0) {
                fileName = [path lastPathComponent];
            }
            if(![fileName hasSuffix:[path pathExtension]]){
                fileName=[fileName stringByAppendingFormat:@".%@",[path pathExtension]];
            }

            [picker setSubject:[@"Send document: " stringByAppendingString:fileName]];

            NSArray *ccRecipients = [NSArray arrayWithObjects: 
                                  [[CustomisationConfig getAppConfig] getCCMail],nil];
            [picker setCcRecipients:ccRecipients];

            NSArray *bccRecipients = [NSArray arrayWithObjects:
                                   [[CustomisationConfig getAppConfig] getBCCMail],nil];
            [picker setBccRecipients:bccRecipients];

            NSData *myData = [path decryptedData];
            [picker addAttachmentData:myData 
                                  mimeType:fileMIMEType(fileName) fileName:fileName];

            NSString *emailBody = [NSString stringWithFormat:
                                  @"\n\nThis file was sent using %@.", 
                                  [DCConfiguration getHumanReadableAppName]  ];
            [picker setMessageBody:emailBody isHTML:NO];

            [self presentViewController:picker animated:true completion:^(void){}];
        }
    }
    @catch (NSException *exception) {
        NSLog(@"ContextMenuViewController sendMailTapped:%@",exception.description);
    }      
}

如果我重新启动iPad并打开应用程序，则仅在第二次点击相应按钮时才会显示选择器。
如果我在此之后再次单击该按钮，则选择器每次都会在第一次触摸时显示，并且效果很好，直到我关闭并重新启动iPad。

将以下内容打印到控制台：

Warning: Attempt to present <MFMailComposeViewController: 0x200cbb70> on <ContextMenuViewController: 0x200cd1a0> whose view is not in the window hierarchy!

Answer 1

什么叫sendMailTapped:方法？ 如果是其接口构建器，则需要将其更改为IBAction而不是void ，并将它们连接到接口构建器中。