为什么会出现 NSException 错误？

Question

我已将以下代码放入...；

NSDictionary *plainPart = [NSDictionary dictionaryWithObjectsAndKeys:@"text/plain",kSKPSMTPPartContentTypeKey,
@"Hello,\n You've just received a new message from the iDHSB iPhone App.\n Here it is: %@",field.text,     
kSKPSMTPPartMessageKey,@"8bit",kSKPSMTPPartContentTransferEncodingKey,nil];

...我收到一个 NSException 错误提示；

*** WebKit discarded an uncaught exception in the webView:shouldInsertText:replacingDOMRange:givenAction: delegate:     
<NSInvalidArgumentException> +[NSDictionary dictionaryWithObjectsAndKeys:]: second object of each pair must be non-nil.  Or, did  
you forget to nil-terminate your parameter list?

这是什么意思？我该怎么做才能解决这个问题？

谢谢，

詹姆斯

Answer 1

您正在尝试在字典初始化中格式化字符串，它期望格式为object, key, object, key, etc..。要解决此问题，请尝试在另一行上创建格式化字符串以清楚起见，然后将其添加为对象和键的一部分

NSString *message = [NSString stringWithFormat:@"Hello,\n You've just received a new message from the iDHSB iPhone App.\n Here it is: %@",
                                                 field.text];
NSDictionary *plainPart = [NSDictionary dictionaryWithObjectsAndKeys:
                              @"text/plain", kSKPSMTPPartContentTypeKey,
                              message, kSKPSMTPPartMessageKey,
                              @"8bit", kSKPSMTPPartContentTransferEncodingKey,nil];

Answer 2

也许你的意思是这样的：

NSDictionary *plainPart = [NSDictionary dictionaryWithObjectsAndKeys:@"text/plain", kSKPSMTPPartContentTypeKey, [NSString stringWithFormat:@"Hello,\n You've just received a new message from the iDHSB iPhone App.\n Here it is: %@",field.text], kSKPSMTPPartMessageKey, @"8bit", kSKPSMTPPartContentTransferEncodingKey,nil];

Answer 3

您缺少一个论点。我计算了 8 个总论点，包括 nil。这意味着您的一个键值对不完整。

Answer 4

尝试首先创建字符串：

NSString *partMessageKey = [NSString stringWithFormat:@"Hello,\n You've just received a new message from the iDHSB iPhone App.\n Here it is: %@",field.text];

然后将此字符串作为对象放入字典中。