Question

这是我的第一个应用程序，我正在尝试实现pull to refresh控制。我遇到了路障。有人可以识别并修复我的代码吗？拉动刷新动画有效但我表中的XML数据不刷新。提前谢谢。

#import "MasterViewController.h"

#import "DetailViewController.h"

@interface MasterViewController () {
    NSXMLParser *parser;
    NSMutableArray *feeds;
    NSMutableDictionary *item;
    NSMutableString *title;
    NSMutableString *link;
    NSString *element;
}
@end

@implementation MasterViewController

- (void)awakeFromNib
{
    [super awakeFromNib];
}

//Paste Blog feed here
- (void)viewDidLoad {
    [super viewDidLoad];
    feeds = [[NSMutableArray alloc] init];
    NSURL *url = [NSURL URLWithString:@"http://Placeholder.xml"];
    parser = [[NSXMLParser alloc] initWithContentsOfURL:url];
    [parser setDelegate:self];
    [parser setShouldResolveExternalEntities:NO];
    [parser parse];
    UIRefreshControl *refreshControl = [UIRefreshControl new];
    [refreshControl addTarget:self action:@selector(refresh:) forControlEvents:UIControlEventValueChanged];
    refreshControl.attributedTitle = [[NSAttributedString alloc] initWithString:@"Pull to refresh..."];
    self.refreshControl = refreshControl;
    [self.tableView reloadData];

}

- (void)refresh:(UIRefreshControl *)sender
{
    // ... your refresh code
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:YES];

    NSURLSession *session = [NSURLSession sharedSession];
    [[session dataTaskWithURL:[NSURL URLWithString:@"http://Placeholder.xml"]
            completionHandler:^(NSData *data,
                                NSURLResponse *response,
                                NSError *error) {

                // handle response
                NSXMLParser *updatedParser = [[NSXMLParser alloc] initWithData:data];
                [updatedParser parse];

                [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];
            }] resume];
    [sender endRefreshing];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}


#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

Answer 1

您需要告诉UITableView何时应该刷新自己。目前您下载了新数据，但是您没有对它做任何事情。

如果您只想加载特定的部分/行范围，则要么在表视图上调用-reloadData方法，要么调用其他重载方法之一。在完成解析已下载的新数据并准备好显示它之后，您应该调用它。

有人可以识别并修复我的iOS拉动以刷新代码吗？

1 个答案: