Question

我正在创建一个RSS Feed应用程序，我的主视图控制器将显示这些Feed。我的应用程序首先没有任何错误，表现良好。最近，我添加了一个导航菜单，如下所示：http://www.appcoda.com/ios-programming-sidebar-navigation-menu/现在导航菜单不是我的问题。我的RSS列表视图完全为空，它显示空单元格。这是我的主视图controller.h：

#import <UIKit/UIKit.h>

@interface MainViewController : UIViewController <NSXMLParserDelegate>

@property (weak, nonatomic) IBOutlet UIBarButtonItem *sidebarButton;
@property (strong, nonatomic) IBOutlet UITableView *tableView;

@end

这是我的主视图Controller.m：

#import "MainViewController.h"
#import "SWRevealViewController.h"
#import "DetailViewController.h"

@interface MainViewController () {

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

}

@end

@implementation MainViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    feeds = [[NSMutableArray alloc] init];
    NSURL *url = [NSURL URLWithString:@"http://images.apple.com/main/rss/hotnews/hotnews.rss"];
    parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
    [parser setDelegate:self];
    [parser setShouldResolveExternalEntities:NO];
    [parser parse];

    // Change button color
    _sidebarButton.tintColor = [UIColor colorWithWhite:0.1f alpha:0.9f];

    // Set the side bar button action. When it's tapped, it'll show up the sidebar.
    _sidebarButton.target = self.revealViewController;
    _sidebarButton.action = @selector(revealToggle:);

    // Set the gesture
    [self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];

}

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

#pragma mark - Table View

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)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)parserDidEndDocument:(NSXMLParser *)parser {

    [self.tableView reloadData];

}

- (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

感谢您的帮助！

Answer 1

您可能希望在以下位置设置断点：

didStartElement：检查解析是否已开始
parserDidEndDocument：检查解析是否完成并重新加载tableview
tableView：numberOfRowsInSection：检查是否正在点击tableview委托方法

您还想检查在Interface Builder中是否正确设置了tableView插座以及委托和数据源

我的tableView显示但它是空的？怎么修？

1 个答案: