PFRelation从PFRelation中删除一个对象，但不是全部

Question

对正在发生的事情的解释:用户在另一个视图中添加了一个作业作为他们的最爱。现在，用户在“收藏夹”选项卡中，并决定不再希望该作业成为他们的收藏夹之一，因此他们滑动以删除该作业。他们点击delete按钮，下面的错误使place...the代码工作正常，但它也删除了用户保存的每一个作业，而不仅仅是删除了一个作业。

我的代码还向我发出了以下警告：

警告:正在主线程上执行长时间运行的操作.中断warnBlockingOperationOnMainThread()来调试.

#import "JobDetailViewController.h"
#import "MyFavoritesTableViewController.h"
#import "Parse/Parse.h"
#import "Job.h"
#import "JobListViewController.h"

@interface MyFavoritesTableViewController ()

@property (nonatomic, strong) NSString *mainTitle;
@property (nonatomic, strong) NSString *subTitle;

@end

@interface MyFavoritesTableViewController ()

@end

@implementation MyFavoritesTableViewController
{}

@synthesize mainTitle;
@synthesize subTitle;



- (id)initWithCoder:(NSCoder *)aCoder
{
    self = [super initWithCoder:aCoder];
    if ([PFUser currentUser]) {
        // Custom the table

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

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

        // 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 = 30;
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];


}

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


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

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

    [self.tableView reloadData];

}

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

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

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath object: (PFObject *)object
{
    static NSString *myJobsTableIdentifier = @"myFavsCell";


    UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:myJobsTableIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:myJobsTableIdentifier];
    }

    // Configure the cell
    PFFile *thumbnail = [object objectForKey:@"imageFile"];
    PFImageView *thumbnailImageView = (PFImageView*)[cell viewWithTag:100];
    thumbnailImageView.image = [UIImage imageNamed:@"AppIcon.png"];
    thumbnailImageView.file = thumbnail;
    [thumbnailImageView loadInBackground];

    UILabel *positionLabel = (UILabel*) [cell viewWithTag:101];
    positionLabel.text = [object objectForKey:@"Position"];
    UILabel *rotationLabel = (UILabel*) [cell viewWithTag:102];
    rotationLabel.text = [object objectForKey:@"Rotation"];
    UILabel *locationLabel = (UILabel*) [cell viewWithTag:103];
    locationLabel.text = [object objectForKey:@"Location"];
    UILabel *typeLabel = (UILabel*) [cell viewWithTag:104];
    typeLabel.text = [object objectForKey:@"Type"];
    return cell;

}

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([segue.identifier isEqualToString:@"showDetailedView"]) {
        NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

        Job *job = [[Job alloc] init];

        JobDetailViewController *destViewController = segue.destinationViewController;

        PFObject *object = [self.objects objectAtIndex:indexPath.row];
        job.position = [object objectForKey:@"Position"];
        job.poc = [object objectForKey:@"POC"];
        job.email = [object objectForKey:@"Email"];
        job.phone = [object objectForKey:@"Phone"];
        job.apply = [object objectForKey:@"Apply"];
        job.imageFile = [object objectForKey:@"imageFile"];
        job.rotation = [object objectForKey:@"Rotation"];
        job.location = [object objectForKey:@"Location"];
        job.type = [object objectForKey:@"Type"];
        job.clearance = [object objectForKey:@"Clearance"];
        job.job_description = [object objectForKey:@"Job_Description"];
        job.qualifications = [object objectForKey:@"Qualifications"];
        job.originalJob = object;
        destViewController.job = job;
    }
}

#pragma mark - UITableViewDelegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [tableView deselectRowAtIndexPath:indexPath animated:YES];

    if ([self.objects count] == indexPath.row) {
        [self loadNextPage];
    } else {
        PFObject *photo = [self.objects objectAtIndex:indexPath.row];
        NSLog(@"%@", photo);

        // Do something you want after selected the cell
    }
}

- (PFQuery *)queryForTable

{
    PFUser *user = [PFUser currentUser];
    PFRelation *relation = [user relationForKey:@"Favorites"];
    PFQuery *myquery = [relation query];
    if (self.pullToRefreshEnabled) {
        myquery.cachePolicy = kPFCachePolicyNetworkOnly;
    }
    return myquery;

}

#pragma mark - DeleteJobViewDelegate


    - (void)tableView:(UITableView *)tableView
commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
forRowAtIndexPath:(NSIndexPath *)indexPath {
    PFUser *user = [PFUser currentUser];
    PFRelation *relation = [user relationForKey:@"Favorites"];
    PFQuery *myquery = [relation query];
    NSArray *array = [myquery findObjects];
        for (PFObject *object in array)
        {
                [relation removeObject:object];
        }

    [user saveInBackground];

    [self.tableView reloadData];
        [self loadObjects];
    }

    @end

Answer 1

问题是，您要从关系中删除所有对象：

NSArray *array = [myquery findObjects];
for (PFObject *object in array)
{
    [relation removeObject:object];
}

您的代码正在通过数组并将每个对象从关系中移除。

您要做的是只删除该单元格的作业。您可以使用indexPath获得这个

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    PFUser *user = [PFUser currentUser];
    PFRelation *relation = [user relationForKey:@"Favorites"];

    [relation removeObject:[self.objects objectAtIndex:indexPath.row]];

    [user saveInBackground];

    [self.tableView reloadData];
    [self loadObjects];
}

你的第二个问题：

警告:正在主线程上执行长时间运行的操作.中断warnBlockingOperationOnMainThread()来调试.

这个警告是因为findObjects是一个同步调用。您应该使用findObjectsInBackground代替。但是如果你做了我上面给你的改变，你就不需要了。