Xcode 4.4 警告：案例值不在枚举类型"MessageComposeResult"(又名"enum MessageComposeResult")中

Question

还有人在Xcode 4.4中收到这个警告吗？

事例值不在枚举类型"MessageComposerResult"（又名"enum MessageComposerresult"）中

MFMailComposeResultFailed包含在文档中取消邮件合成接口时返回的结果代码中。但是，文档列出了它，但GCC警告说它不是MessageComposerResult中的枚举。为什么？

    case MFMailComposeResultFailed:{
        //do something here
    }
        break;

以下是调用此情况的扩展方法（我已将此枚举注释为禁用警告）：

- (void)messageComposeViewController:(MFMessageComposeViewController *)controller didFinishWithResult:(MessageComposeResult)result {
UIAlertView *errormsg = nil;
// Notifies users about errors associated with the interface
switch (result)
{
    case MFMailComposeResultCancelled:
    {
        //Do something, If you need to
        NSString *msgtitle = @"Cancelled Mail";
        NSString *Bodymsg = @"Email Has been Cancelled by USER. You may continue to make modifications to the current attendance data at this point.";
        errormsg = [[UIAlertView alloc] initWithTitle:msgtitle message:Bodymsg delegate:self cancelButtonTitle:@"Close" otherButtonTitles:nil];
    }
        break;
    case MFMailComposeResultSaved:{/*Do nothing at this point*/}
        break;
         //NOTE: MFMailComposeResultFailed is included in Result codes returned when the mail composition interface is dismissed. However the documentation lists it but the GCC warns it is NOT an enum within MessageComposeResult. May be an Apple Bug.
    /*case MFMailComposeResultFailed:{
        NSString *title = @"Unable to Send Mail";
        NSString *msg = @"Failed:nmessage was not saved or queued, possibly due to an error.nCheck your mail sent or draft items.";
        errormsg = [[UIAlertView alloc] initWithTitle:title message:msg delegate:self cancelButtonTitle:@"Close" otherButtonTitles:nil];
    }
        break;
       */  
    case MFMailComposeResultSent:{
        NSString *title = @"Mail Sent";
        NSString *msg = @"Attendance Email has been sent. Thank you.";
        errormsg = [[UIAlertView alloc] initWithTitle:title message:msg delegate:self cancelButtonTitle:@"Close" otherButtonTitles:nil];
        //clean up data
        //code here irrelevant
        //set a completed flag for sent email in system
        //display Alert and dismiss the mail composer view here
        UIAlertView *alertView = nil;
        if (result) {
            alertView = [[UIAlertView alloc] initWithTitle:@"AttendanceViewController: viewDidLoad" message:@"updateProgressOfClassInstance FAILED" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        }
        if (alertView != nil) {
            [alertView show];
        }
    }
        break;
    default:
        break;
}
//dismiss view and display any errors here.
[self dismissModalViewControllerAnimated:YES];
if (errormsg != nil) {
    [errormsg show];
}

我希望这能为你们澄清。谢谢

（更新）好的，我的代码中有几个问题，我没有意识到。我修复了它们，下面是正确的switch语句。

switch (result)
{
    case MessageComposeResultCancelled:
    {
        //Do something, If you need to!
    }
        break;
    case MessageComposeResultFailed:{
        //Do something else, If you need to!!
    }
        break;
    case MessageComposeResultSent:{
        //Do something user friendly, If you need to!
    }
        break;
    default:
        break;
}

在自由的世界里继续摇滚吧，在stackoverflow上！哇！

Answer 1

您混淆了错误代码。结果枚举具有您认为有效的三个值。

"MFMailComposeResultFailed"值在以下委托方法的错误范围内返回：

- (void)mailComposeController:(MFMailComposeViewController*)controller didFinishWithResult:(MFMailComposeResult)result error:(NSError*)error

看看这个去文档页面的底部：

MFMailComposeViewController Class Reference