Question

我正在尝试在RSS feed表上实现一个pull-to-refresh功能。加载应用程序时列表正常拉动，但我基本上需要复制下拉列表。

有人可以帮忙解释为什么代码无效吗？

#import "RSSTableViewController.h"
#import "RSSDetailViewController.h"

@interface RSSTableViewController () {


    NSXMLParser *parser;
    NSMutableArray *feeds;
    NSMutableDictionary *item;
    NSMutableString *title;
    NSMutableString *link;
    NSString *element;

}

@end

@implementation RSSTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // RSS Settings
    feeds = [[NSMutableArray alloc] init];
    NSURL *url = [NSURL URLWithString:@"http://external.example.co.uk/newpost/example.rss"];
    parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
    [parser setDelegate:self];
    [parser setShouldResolveExternalEntities:NO];
    [parser parse];


    UIRefreshControl *refresh = [[UIRefreshControl alloc] init];
     refresh.attributedTitle = [[NSAttributedString alloc] initWithString:@"Pull to Refresh"];
     [refresh addTarget:self
                 action:@selector(refreshView:)
                forControlEvents:UIControlEventValueChanged];
     self.refreshControl = refresh;


}


- (void)refreshView:(UIRefreshControl *)refresh {
         refresh.attributedTitle = [[NSAttributedString alloc] initWithString:@"Refreshing news feed..."];

         // Refresh Logic
    NSURL *url = [NSURL URLWithString:@"http://external.example.co.uk/newpost/example.rss"];
    parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
    [parser setDelegate:self];
    [parser setShouldResolveExternalEntities:NO];
    [parser parse];


        // Set the timestamp
         NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
         [formatter setDateFormat:@"MMM d, h:mm a"];
         NSString *lastUpdated = [NSString stringWithFormat:@"Last updated: %@",
                                  [formatter stringFromDate:[NSDate date]]];
         refresh.attributedTitle = [[NSAttributedString alloc] initWithString:lastUpdated];
         [refresh endRefreshing];
         [self.tableView reloadData];
}



- (void)parserDidEndDocument:(NSXMLParser *)parser {
    [refreshView endRefreshing]; //'Use of undeclared identifier 'refresh view'//
    [self.tableView reloadData];
}


- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    return feeds.count;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
    cell.textLabel.text = [[feeds objectAtIndex:indexPath.row] objectForKey:@"title"];

    return cell;
}



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

    element = elementName;

    if ([element isEqualToString:@"item"]) {
        item = [[NSMutableDictionary alloc]init];
        title = [[NSMutableString alloc]init];
        link = [[NSMutableString alloc]init];
    }
}



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

    if ([elementName isEqualToString:@"item"]) {
        [item setObject:title forKey:@"title"];
        [item setObject:link forKey:@"link"];
        [feeds addObject:[item copy]];
    }
}



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

    if ([element isEqualToString:@"title"]) {
        [title appendString:string];
    }
    else if ([element isEqualToString:@"link"]) {
        [link appendString:string];
    }
}


-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {

    if ([[segue identifier] isEqualToString:@"showDetail"]) {
        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
        NSString *string = [feeds[indexPath.row] objectForKey:@"link"];
        [[segue destinationViewController] setUrl:string];
    }
}
@end

有人有任何想法吗？

Answer 1

代码工作正常需要删除parserDidEndDocument中包含错误的行。

然后，我必须在[feeds removeAllObjects]行下添加//Refresh Logic以清除当前的表格内容。

谢谢你们。

Objective-C拉动刷新

1 个答案: