为什么我收到“函数‘PerformXMLXPathQuery’的隐式声明”警告？

Question

为什么我收到“函数 'PerformXMLXPathQuery' 的隐式声明”警告？

NSString *response = [request responseString];  
NSString* xPathQuery = [NSString stringWithFormat:@"//ExtendedData"];  
NSArray* myArray = PerformXMLXPathQuery([response dataUsingEncoding:NSUTF8StringEncoding ],xPathQuery);

Answer 1

警告表明编译器找不到为 PerformXMLXPathQuery 函数声明的原型。检查是否已导入声明函数的头文件。