connectionDidFinishLoading完成后无法重新加载UITableView

Question

I am downloading and parsing JSON objects to build a "news feed" to populate a UITableView. The very last line of code I have in the connectionDidFinishLoading delegate method is:

[tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO];

However, my break points in the - (UITableViewCell *)tableView:(UITableView *)mytableView cellForRowAtIndexPath:(NSIndexPath *)indexPath method are not hit. (They are hit when the app first launches)

So for whatever reason even though I am calling the reloadData on the main thread; it doesn't appear to be firing. I tried just [tableView reloadData] and that did not work.

Here is my connectionDidFinishLoading method:

- (void)connectionDidFinishLoading:(NSURLConnection *)connection 
{       

    //NSString *responseString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];

    NSArray *publicTimeline = [NSJSONSerialization JSONObjectWithData:responseData options:0 error:nil]; 

    NSUInteger newsStreamCount = [publicTimeline count];

    // Initialize the collection and the dictionary
    newsItemManager.newsItemCollection = [[NSMutableArray alloc] initWithCapacity:newsStreamCount];
    NSMutableArray *dictOfNewsItems = [[NSMutableArray alloc] initWithCapacity:newsStreamCount];

    // From the JSON object, parse out the individual news item JSON objects and 
    // put them into a dictionary.
    for (int i = 0; i < newsStreamCount; i++)
    {
        NSDictionary *item = [publicTimeline objectAtIndex:i];
        [dictOfNewsItems addObject:item];
    }

    // For each news item JSON object, extract out the information we need for our
    // news manager class
    for (int i = 0; i < newsStreamCount; i++)
    {
        NSString *userName = [[dictOfNewsItems objectAtIndex:i] valueForKey:@"Title"];
        NSString *message = [[dictOfNewsItems objectAtIndex:i] valueForKey:@"Content"];
        NSString *imgUrl = [[dictOfNewsItems objectAtIndex:i] valueForKey:@"https://si0.twimg.com/logo_normal.jpg"];


        NewsItem *newsItem = [[NewsItem alloc] initWithBasicInfo:userName :message :imgUrl];


        [newsItemManager.newsItemCollection addObject:newsItem];
    }

    [tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO];
}

Here is my header file:

#import <UIKit/UIKit.h>

@interface NewsViewController : UITableViewController

@property (nonatomic, retain) NSMutableArray* newsItemArray;
@property (nonatomic, retain) NSMutableData *responseData;
@property (nonatomic, retain) IBOutlet UITableView *tableView;

@end

Here is my implementation:

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Uncomment the following line to preserve selection between presentations.
    // self.clearsSelectionOnViewWillAppear = NO;

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;

    self.title = @"News";

    //self.newsItemArray = [[NSMutableArray alloc] initWithObjects:@"One", @"Two", @"Three", nil];

    tableView.rowHeight = 75.0;


    responseData = [NSMutableData data];        
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://blah.com/api/news"]];
    (void)[[NSURLConnection alloc] initWithRequest:request delegate:self];

}

Thanks, Flea

Answer 1

如果您的connectionDidFinish ...方法位于tableViewController类中，则可能只需要

[self.tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO];

Answer 2

The overall problem was my newsItemManager.newsItemCollection was not being initialized properly and was returning null the entire time, thus when the UITableView was trying to load data; there was nothing to load.

I thought I had checked for this but one of those problems of staring at the computer all day and missing the obvious.