ios - 为什么 MFMailComposeViewController 返回 MFMailComposeResultFailed？

Question

我的应用程序遇到了一个奇怪的问题，我需要你的帮助!
我正在使用 MFMailComposeViewController 发送带有附件数据的电子邮件。附件可以是 PDF、CSV 或 XLS 文件。也可以将 ZIP 文件添加到邮件中。

在大多数情况下一切正常，但有时(实际上经常)，当附件是 XLS 并且添加了 ZIP 时，我收到多个内存警告并且 Composer 返回 MFMailComposeResultFailed，错误根本没有帮助(只说代码错误 1，“操作无法完成。(MFMailComposeErrorDomain 错误 1。)”)。

我的问题是为什么要这样做？我假设内存警告告诉我有些事情没有得到很好的管理，但我无法弄清楚是什么......

这是我发送邮件的代码

-(void) sendMail {

    MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init]; 
    [self prepareMailPicker:picker];

    NSString *filePath = [self getFilePath:pType];

    NSString *zipFile = [self getZipPath];

    NSString *mimeType;
    int userPhoto = [User getCSVPhoto];

    switch (pType) {
        case EPDF:
            mimeType = @"application/pdf";
            userPhoto = [User getPDFPhoto];
            break;
        case ECSV:
            mimeType = @"text/csv";
            break;
        case EExcel:
            mimeType = @"application/vnd.ms-excel";
            break;

        default:
            break;
    }

    NSData *attachmentData = [NSData dataWithContentsOfFile:filePath];
    [picker addAttachmentData:attachmentData mimeType:mimeType fileName:[filePath lastPathComponent]];

    if (userPhoto == 1 && shouldAddZip) {
        NSData *zipData = [NSData dataWithContentsOfFile:zipFile];
        [picker addAttachmentData:zipData mimeType:@"application/zip" fileName:[zipFile lastPathComponent]];
    }

    shouldAddZip = NO;

    [self presentModalViewController:picker animated:YES];
}

-(void) prepareMailPicker:(MFMailComposeViewController*)picker {

    picker.mailComposeDelegate = (id<MFMailComposeViewControllerDelegate>)self;

    picker.navigationBar.tintColor = grayDark;

    [picker setSubject:[TextManager textForKey:@"EMAIL_SUBJECT"]];

    NSString *email = [[User currentUser] getEmail];

    if (email && ![email isEqualToString:@""])
        [picker setToRecipients:[NSArray arrayWithObject:email]];

    NSString *emailBody = [TextManager textForKey:@"EMAIL_TEXT"];
    [picker setMessageBody:emailBody isHTML:YES];
}

任何帮助将不胜感激!

编辑:正如@matt 所要求的，这里有一个日志来证明没有任何设置为 nil :

filePath : /var/mobile/Applications/A57F5CD2-E3FE-4417-8810-D746A22CF434/Documents/iNdF_Export_2012-11-19.xls
zipFile : /var/mobile/Applications/A57F5CD2-E3FE-4417-8810-D746A22CF434/Documents/iNdF_recus_2012-11-19.zip
attachmentData : (NSConcreteData *) <0x1d9c3c20> 53 874 bytes
zipData : (NSConcreteData *) <0x1f989100> 6 838 456 bytes

Answer 1

正如您所说，考虑到您收到的内存警告，问题似乎很可能与内存管理有关。

您的代码保留了对第一个文件中 attachmentData 的引用计数，即使它出去获取第二个文件的 zipData 也是如此。在内部，选择器可能正在复制该数据......

因此，您越能尽早释放对大数据的引用，就越有可能不会收到内存警告。

如果问题是选择器由于内存不足而无法完成附件，而您可以通过提前发布来解决这个问题，那么按以下方式分解代码可能会对您有所帮助。

- (void)sendMailPicker:(MFMailComposeViewController*)picker addAttachmentUsingMimeType:(NSString*)mimeType {
    NSString *filePath = [self getFilePath:pType];
    NSData *attachmentData = [NSData dataWithContentsOfFile:filePath];
    [picker addAttachmentData:attachmentData mimeType:mimeType fileName:[filePath lastPathComponent]];
}

- (void)sendMailAddPhotoUsingPicker:(MFMailComposeViewController*)picker {
    NSString *zipFile = [self getZipPath];
    NSData *zipData = [NSData dataWithContentsOfFile:zipFile];
    [picker addAttachmentData:zipData mimeType:@"application/zip" fileName:[zipFile lastPathComponent]];
}

- (void)sendMail {

    MFMailComposeViewController *picker = [[MFMailComposeViewController alloc] init]; 
    [self prepareMailPicker:picker];

    NSString *mimeType;
    int userPhoto = [User getCSVPhoto];

    switch (pType) {
        case EPDF:
            mimeType = @"application/pdf";
            userPhoto = [User getPDFPhoto];
            break;
        case ECSV:
            mimeType = @"text/csv";
            break;
        case EExcel:
            mimeType = @"application/vnd.ms-excel";
            break;

        default:
            break;
    }

    [self sendMailPicker:picker addAttachmentUsingMimeType:mimeType];
    if (userPhoto == 1 && shouldAddZip) {
        [self sendMailAddPhotoUsingPicker:picker];
    }

    shouldAddZip = NO;

    [self presentModalViewController:picker animated:YES];
}