在此处输入代码您将检查元素是否不为零而不是它存在.. as
TBXMLElement *rootElement = [xml rootXMLElement];
TBXMLElement *yourTag = [TBXML childElementNamed:@"YourTagName" parentElement:rootElement];
if(yourTag)
NSLog(@"This element exists");
else
NSLog(@"This element does not exist");