Question

您好我有一个解析器可以测试可能的错误，例如D_TBXML_ELEMENT_TEXT_IS_NIL。如果obj1为nil且obj2有文本（NSError *），则错误仍返回非0值。除了重新分配0值之外，有没有办法清除以前的值？

我的代码是

- (void) parseOthers: (TBXMLElement *) element
{
    do {
        if (element -> firstChild)
        [self parser:element->firstChild];
        if ([[TBXML elementName:element] isEqualToString:@"myXML"]) {

        MyClass *myClass = [[MyClass alloc] init];
        NSError *error = nil;


        // TBXML element obj1 has nil text.
        myClass.myObject1 = [TBXML textForElement:[TBXML childElementNamed:@"obj1" parentElement:element] error:&error];
        if(error){
            NSLog(@"error in myObject1 > %@",[error localizedDescription]);
            // Causes the second object to return a non nil error if I don't use the code below. error = nil;
            error = nil;
        }


        // TBXML element obj2 has text but returns D_TBXML_ELEMENT_TEXT_IS_NIL if error = nil above isn't added.
        myClass.myObject2 = [TBXML textForElement:[TBXML childElementNamed:@"obj2" parentElement:element] error:&error];
        if(error){
            NSLog(@"error in myObject2 > %@",[error localizedDescription]);
            error = nil;
        }


        [myArray addObject:myClass];

        }
    } while ((element = element->nextSibling));
}

Answer 1

除非出现错误（方法返回error），否则请勿检查nil。

- (void) parseOthers: (TBXMLElement *) element
{
    do {
        if (element -> firstChild)
        [self parser:element->firstChild];
        if ([[TBXML elementName:element] isEqualToString:@"myXML"]) {

        MyClass *myClass = [[MyClass alloc] init];
        NSError *error = nil;


        // TBXML element obj1 has nil text.
        myClass.myObject1 = [TBXML textForElement:[TBXML childElementNamed:@"obj1" parentElement:element] error:&error];
        if(!myClass.myObject1){
            NSLog(@"error in myObject1 > %@",[error localizedDescription]);
            // Causes the second object to return a non nil error if I don't use the code below. error = nil;
            error = nil;
        }


        // TBXML element obj2 has text but returns D_TBXML_ELEMENT_TEXT_IS_NIL if error = nil above isn't added.
        myClass.myObject2 = [TBXML textForElement:[TBXML childElementNamed:@"obj2" parentElement:element] error:&error];
        if(!myClass.myObject2){
            NSLog(@"error in myObject2 > %@",[error localizedDescription]);
            error = nil;
        }


        [myArray addObject:myClass];

        }
    } while ((element = element->nextSibling));
}

NSError在TBXML中是否可重用？

1 个答案: