Question

我想根据xml格式的标题和链接从网站获取更新。

我已尝试使用下面的代码，但它无效。在控制台中，它显示消息：

2011-11-03 14：45：05.987 tabbar [673：e903] * 终止应用程序未捕获的异常'NSInvalidArgumentException'，原因：' - [NSCFString isEqualtostring：]：无法识别的选择器发送到实例0x5746830'

如果我再次运行，表视图正在加载，但表格单元格中没有数据。

它在if ([elementName isEqualtostring:@"item"])行显示此消息：

程序接收信号SIGABRT

-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    classelement = elementName;
    if ([elementName isEqualtostring:@"item"])
    {
        itemselected = YES;
        multitle = [[NSMutableString alloc]init];
        mullink = [[NSMutableString alloc]init];
    }
}

-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedname:(NSString *)qName
{
    if ([elementName isEqualToString:@"item"])
    {
        itemselected = NO;
        [titlearray addObject:multitle];
        [linkarray addObject:mullink];
        [multitle release];
        [mullink release];

        [self.tbl reloadData];
    }
}

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    if (itemselected)
    {
        if ([classelement isEqualToString:@"title"]) 
        {
            NSLog(@"%@",string);
            [multitle appendString:multitle];
        }
        else if([classelement isEqualToString:@"link"])
        {
            [multitle appendString:string];
        }
    }
}

Answer 1

如果您直接从网站上阅读，很可能会收到“无效”字符。一旦解析器看到这些无效字符，它就会崩溃。我建议使用“HPPLE Parser”。如果出现无效字符，它的效果会更好，不会崩溃。

这里的Hpple信息：http://blog.objectgraph.com/index.php/2010/02/24/parsing-html-iphone-development/

Answer 2

最后我明白了。我所做的是我已经使用了两个NSMutableArray和两个NSMutableString，我将这些项添加到字符串中，然后将这些字符串附加到两个数组中。

(void)viewDidLoad
{

    titlearray = [[NSMutableArray alloc]init];
    linkarray = [[NSMutableArray alloc]init];

    NSString *rssaddress =@"http://www.greenday.com/rss";
    NSURL *url = [NSURL URLWithString:rssaddress];
    xmlparser = [[NSXMLParser alloc]initWithContentsOfURL:url];
    [xmlparser setDelegate:self];
    [xmlparser parse];


    [super viewDidLoad];
}

(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{

    classelement = elementName;



    if([elementName isEqualToString:@"item" ])
    {
        itemselected = YES;
        titlestrng = [[NSMutableString alloc]init];
        linkstrng = [[NSMutableString alloc]init];

    }

}

(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{

    if([elementName isEqualToString:@"item" ])
    {
        itemselected = NO;
        [titlearray addObject:titlestrng];
        [linkarray addObject:linkstrng];


        [titlestrng release];
        [linkstrng release];


        [self.tb reloadData];
    }
}


(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{

    if(itemselected)
    {
        if([classelement isEqualToString:@"title"])
        {
            [titlestrng appendString: string];
                    NSLog(@"%@",titlestrng);
        }

        else if ([classelement isEqualToString:@"link"])
        {
            [linkstrng appendString:string];
            NSLog(@"%@",linkstrng);

        }
    }
}

如何使用NSXMLParser解析网站上的数据

2 个答案: