IOS FindObjectsInBackgroundWithBlock - ＆gt; setNeedsDisplay

Question

我正在运行一个Parse程序，该程序使用'findObjectsInBackgroundWithBlock'抓取数据并从中创建对象。一旦完成，我更新自我，然后调用'[self.tableView setNeedsDisplay]'，但我的显示没有任何变化，也没有显示新项目。难道我做错了什么？以及如何修复它？

-(void)pullDown{
NSLog(@"Began PullDown");
NSMutableArray *bugs = [NSMutableArray arrayWithObjects: nil];

//NSMutableArray *bugs = [NSMutableArray arrayWithObjects: nil];
NSLog(@"Journal POSTS");
PFQuery *queryJournal = [PFQuery queryWithClassName:@"Post"];
[queryJournal whereKey:@"user" equalTo:[PFUser currentUser]];
NSLog(@"WHEN ARE YOU CALLED?");
[queryJournal findObjectsInBackgroundWithBlock:^(NSArray *posts, NSError *error) {
    if (!error) {
        // The find succeeded.
        //NSLog(@"Successfully retrieved %@ Posts.", posts);
        // Do something with the found objects

        for (PFObject *object in posts) {
            int rating = object[@"Rating"];
            NSLog(@"RATING object: %@; int: %i", object[@"Rating"], rating);
            MSJournalerDoc *post = [[MSJournalerDoc alloc] initWithTitle:object[@"Title"] rating:rating thumbImage:object[@"imageFile"] fullImage:object[@"imageFile"]];
            [bugs addObject:post];
        }
        NSLog(@"HELL YA");
        NSLog(@"THE LIST: %@", bugs);
        self.bugs = bugs;
        NSLog(@"END OF LOOOOOOOOOOOOOOOPS %lu", bugs.count);
        [self.tableView setNeedsDisplay];
        NSLog(@"MOAR");
    } else {
        // Log details of the failure
        NSLog(@"Error: %@ %@", error, [error userInfo]);
    } 
}];
}




- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.

    if ([PFUser currentUser]) {
        NSLog(@"CURRENT USER");
        [self pullDown];
        NSLog(@"POST CURRENT USER");
    }
    else{
        [self createUser];
        [self createBug];
    }


self.navigationItem.leftBarButtonItem = self.editButtonItem;

UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject:)];
self.navigationItem.rightBarButtonItem = addButton;

//Change the Title
self.title = @"Posts";

self.navigationItem.leftBarButtonItem = self.editButtonItem;
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc]
                                          initWithBarButtonSystemItem:UIBarButtonSystemItemAdd
                                          target:self action:@selector(addTapped:)];

NSLog(@"Finished ViewDidLoad");
}

Answer 1

你有几个不同的问题。

首先，在视图上调用setNeedsDisplay会导致重绘，但这对于表视图来说还不够，因为它的数据都没有更新。相反，您需要调用reloadData来更新数据并自动触发重绘。

其次，您正在尝试使用parse返回的图像，但解析永远不会返回图像（至少不会直接返回）。因此，访问object[@"imageFile"]会返回PFFile，而不是UIImage。您需要先致电getDataInBackgroundWithBlock:以获取图像数据，然后才能使用它。