PFQueryTableViewController 找不到我的班级

Question

登录和注册过程在我的代码中运行良好，因此我有一个现有的用户类，但我收到此错误 由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因：'setObjectForKey：对象不能为零（键：类名）' 首先抛出调用堆栈： 当我启动模拟器时。所以我不明白哪个类丢失或为零，因为我已将 User 类设置为查询。 （我想在列表中显示用户名）

@interface Contacts ()

@end

@implementation Contacts


- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom the table

        // The className to query on
        self.parseClassName = @"User";

        // The key of the PFObject to display in the label of the default cell style
        self.textKey = @"username";

        // The title for this table in the Navigation Controller.
        self.title = @"Title";

        // Whether the built-in pull-to-refresh is enabled
        self.pullToRefreshEnabled = YES;

        // Whether the built-in pagination is enabled
        self.paginationEnabled = YES;

        // The number of objects to show per page
        self.objectsPerPage = 5;
    }
    return self;
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];

    PFUser *currentUser = [PFUser currentUser];
    if (currentUser) {
        NSLog(@"Current user: %@", currentUser.username);
    } else {
        [self performSegueWithIdentifier:@"goLogin" sender:self];
    }

}


- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated
{
    [super viewDidDisappear:animated];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - Parse

- (void)objectsDidLoad:(NSError *)error {
    [super objectsDidLoad:error];

    // This method is called every time objects are loaded from Parse via the PFQuery
}

- (void)objectsWillLoad {
    [super objectsWillLoad];

    // This method is called before a PFQuery is fired to get more objects
}


// Override to customize what kind of query to perform on the class. The default is to query for
// all objects ordered by createdAt descending.
- (PFQuery *)queryForTable {
    PFQuery *query = [PFQuery queryWithClassName:self.parseClassName];

    // If no objects are loaded in memory, we look to the cache first to fill the table
    // and then subsequently do a query against the network.
    if ([self.objects count] == 0) {
        query.cachePolicy = kPFCachePolicyCacheThenNetwork;
    }

    [query orderByAscending:@"priority"];

    return query;
}



// Override to customize the look of a cell representing an object. The default is to display
// a UITableViewCellStyleDefault style cell with the label being the first key in the object.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath object:(PFObject *)object {
    static NSString *CellIdentifier = @"contactCell";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    }

    // Configure the cell
    cell.textLabel.text = [object objectForKey:@"text"];
    cell.detailTextLabel.text = [NSString stringWithFormat:@"Priority: %@", [object objectForKey:@"priority"]];

    return cell;
}


/*
 // Override if you need to change the ordering of objects in the table.
 - (PFObject *)objectAtIndex:(NSIndexPath *)indexPath {
 return [objects objectAtIndex:indexPath.row];
 }
 */

/*
 // Override to customize the look of the cell that allows the user to load the next page of objects.
 // The default implementation is a UITableViewCellStyleDefault cell with simple labels.
 - (UITableViewCell *)tableView:(UITableView *)tableView cellForNextPageAtIndexPath:(NSIndexPath *)indexPath {
 static NSString *CellIdentifier = @"NextPage";
 UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
 if (cell == nil) {
 cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
 }
 cell.selectionStyle = UITableViewCellSelectionStyleNone;
 cell.textLabel.text = @"Load more...";
 return cell;
 }
 */

#pragma mark - Table view data source

/*
 // Override to support conditional editing of the table view.
 - (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
 {
 // Return NO if you do not want the specified item to be editable.
 return YES;
 }
 */

/*
 // Override to support editing the table view.
 - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
 {
 if (editingStyle == UITableViewCellEditingStyleDelete) {
 // Delete the row from the data source
 [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
 }
 else if (editingStyle == UITableViewCellEditingStyleInsert) {
 // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
 }
 }
 */

/*
 // Override to support rearranging the table view.
 - (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
 {
 }
 */

/*
 // Override to support conditional rearranging of the table view.
 - (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
 {
 // Return NO if you do not want the item to be re-orderable.
 return YES;
 }
 */

#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [super tableView:tableView didSelectRowAtIndexPath:indexPath];
}

-(void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqual:@"goLogin"]) {
        [segue.destinationViewController setHidesBottomBarWhenPushed:YES];
    }
}
- (IBAction)logoutButton:(id)sender {
    [PFUser logOut];
    [self performSegueWithIdentifier:@"goLogin" sender:self]; }
@end

Answer 1

您确定调用了initWithStyle 方法吗？如果您使用情节提要，则需要使用initWithCoder 而不是initWithStyle。

更新

另外，替换

    // The className to query on
    self.parseClassName = @"User";

与

    // The className to query on
    self.parseClassName = @"_User";