小编Dar*_*ang的帖子

为了支持iPhone OS 3.x和4.0,我以编程方式控制MFMessageComposeViewController这样的功能(仅在OS版本为4.0或更高版本时使用它):

// if iPhone OS version >= 4.0
if (os_version_num >= 4) {
   MFMessageComposeViewController *controller = [[MFMessageComposeViewController alloc] init];
   if([MFMessageComposeViewController canSendText])
   {
      controller.body = text;
      controller.recipients = [NSArray arrayWithObjects: nil];
      controller.messageComposeDelegate = self;
      [self presentModalViewController:controller animated:YES];
      [controller release];
   }
}

但是,当我尝试在iPhone 3.1.3设备上运行它时,我立即收到以下错误(甚至在应用程序加载之前):

dyld: Symbol not found: _OBJC_CLASS_$_MFMessageComposeViewController
  Referenced from: /var/mobile/Applications/7232C474-FAD5-4E28-ABC5-8520F62300B0/TextMe.app/TextMe
  Expected in: /System/Library/Frameworks/MessageUI.framework/MessageUI

数据格式化程序暂时不可用,将在"继续"后重试.(此时调用dlopen不安全.)

我究竟做错了什么？