ios - 数组在 numberOfRowsInSection 中等于 0

Question

我有一个 UITableViewController 用于显示本地业务对象列表的名称。我用过这个 UITableViewController以前从 .csv 文件中读取信息，这一切都在正常工作，并在我的 UITableViewController 中完美地显示了公司名称。

但是，我最近将所有这些信息都移到了 Parse.com，现在我正尝试在我当前的 UITableViewController 中读取和显示来自 Parse.com 的信息。

我正在尝试重构代码而不是在这里使用 Parse.com 的教程: https://www.parse.com/docs/ios_guide#ui-tables/iOS

在我的 viewDidLoad 方法中，我调用我自己的方法 [self initializeContent] 执行 PFQuery 来检索适合的对象列表特定条件，然后将对象保存在 NSMutableArray 中。

这执行得很好，我可以看到业务对象正在通过我的 [self initializeContent] 方法中的 NSLogs 检索并保存到 NSMutableArray(数据数组)。但是，当单步执行代码时，我的 dataArray 在 numberOfSectionsInTableView 方法中为 0。因此，我没有在 UITableViewController 中看到显示的企业名称。

numberOfSectionsInTableView 是否在 viewDidLoad 方法之前执行，这意味着我的 dataArray 将始终为 0？

我已经逐步检查了代码，但无法弄清楚我的问题出在哪里。

下面是我的代码 - 我尽可能多地包含了代码，以帮助确定我的问题出在哪里。

BusinessDetailTableViewController.h

#import <UIKit/UIKit.h>
#import <Parse/Parse.h>

@interface BusinessDetailTableViewController : UITableViewController

@property (nonatomic, strong) NSMutableArray *dataArray;
@property (nonatomic, strong) NSMutableArray *defaultBusinessArrayMutable;
@property (nonatomic, assign) int tagNumber;
    @property (nonatomic, strong) NSString *className;

@end

BusinessDetailTableViewController.m

#import "BusinessDetailTableViewController.h"
#import "BusinessDetailContent.h"
#import "DetailViewController.h"
#import <Parse/Parse.h>

@interface BusinessDetailTableViewController ()
@end

@implementation BusinessDetailTableViewController

@synthesize dataArray;
@synthesize defaultBusinessArrayMutable;
@synthesize tagNumber;
@synthesize className;

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self initializeArrays];
    [self initializeContent];
}

- (void) initializeArrays
{
    dataArray                   = [[NSMutableArray alloc] init];
    defaultBusinessArrayMutable = [[NSMutableArray alloc] init];
}

- (void) initializeContent
{
    NSLog(@"Class Name: %@", className);  // Shows the correct className
    [self queryParse:className];
}

- (void) queryParse:(NSString *) className
{
    PFQuery *query = [PFQuery queryWithClassName:self.className];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
    {
         if (!error)
         {
             NSLog(@"Successfully Retrieved %d Objects.", (int)objects.count);    // Shows how many objects are retrieved

             for (PFObject *object in objects)
             {
                 BusinessDetailContent *businessDetailContent = [[BusinessDetailContent alloc] init];        
                 businessDetailContent.no           = object[@"ID"];
                 businessDetailContent.companyName  = object[@"Company_Name"];
                 businessDetailContent.address      = object[@"Address"];
                 businessDetailContent.tel          = object[@"Tel"];
                 businessDetailContent.email        = object[@"Email"];
                 businessDetailContent.website      = object[@"Website"];
                 businessDetailContent.details      = object[@"Details"];
                 businessDetailContent.imageName    = object[@"Image_ID"];

                 // The information here is retrieved correctly  
                 NSLog(@"BUSINESS DETAIL CONTENT - ID: %@, Company Name: %@, Address: %@, Tel: %@, Email: %@, Website: %@, Details: %@, Image_Name: %@",
                           businessDetailContent.no, businessDetailContent.companyName, businessDetailContent.address, businessDetailContent.tel,
                           businessDetailContent.email, businessDetailContent.website, businessDetailContent.details,
                           businessDetailContent.imageName);


                 [defaultBusinessArrayMutable addObject:businessDetailContent];


                 NSString *strFromInt = [NSString stringWithFormat:@"%d", tagNumber];

                 if (!([strFromInt isEqualToString:@"3"] || [strFromInt isEqualToString:@"10"]))
                     {
                         [dataArray addObject:defaultBusinessArrayMutable];
                         NSLog(@"Default Business Array Mutable Count: %i", (int)dataArray.count);
                     }
                 }
             }
         }
         else
         {
             NSLog(@"Error retrieving objects: %@ %@", error, [error userInfo]);
         }
     }];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@" cellForRowAtIndexPath ");      // This is not executed

    static NSString *CellIdentifier = @"Cell";
    NSLog(@"Cell Identifier: %@", CellIdentifier);

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

    // Configure the cell
    NSArray *cellArray = [dataArray objectAtIndex:indexPath.section];

    BusinessDetailContent *businessDetailContent = [cellArray objectAtIndex:indexPath.row];

    cell.textLabel.text = businessDetailContent.companyName;
    NSLog(@"Cell Textlabel Text: %@", cell.textLabel.text);

    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

    return cell;
}

- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@" didSelectRowAtIndexPath ");
    [self performSegueWithIdentifier:@"businessDetailSegue" sender:self];
}



- (NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
    NSLog(@"numberOfRowsInSection returning: %d", (int)[dataArray count]);      
    return [dataArray count];              // dataArray = 0
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSMutableArray *array = [dataArray objectAtIndex:section];

    return [array count];
}


- (void) prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSLog(@"PrepareForSegue: %@", segue.identifier);
    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];

    if ([segue.identifier isEqualToString:@"businessDetailSegue"] && indexPath)
    {
        NSArray *selectedRowArray = [dataArray objectAtIndex:indexPath.section];

        BusinessDetailContent *selectedContent = [selectedRowArray objectAtIndex:indexPath.row];

        DetailViewController *detailController = segue.destinationViewController;
        detailController.businessDetailContent = selectedContent;
    }
}a
@end

编辑:我添加了 [self.tableView reloadData]；到我的 findObjectsInBackgroundWithBlock 方法的末尾，正如许多人所建议的那样，现在我正在使用 numberOfSectionsInTableView 方法，但是 dataArray 仍然是 0。看起来我的代码正在执行两次，正如控制台打印所看到的那样？

对于我的 queryParse 方法中的 dataArray，它返回 18 个对象——但应该只有 9 个。从控制台打印 Hotel Array Count 从 2 开始，之后每次递增 2。

我的 numberOfRowsInSection 现在被执行了两次，但在 Parse.com 查询之前。

我完全被这个困住了。

Answer 1

@Hans Moolman，是的，你是对的，你只需要在解析完成后调用 TableView 的重新加载方法。即

- (NSMutableArray *) queryParse:(NSString *) className
{
    PFQuery *query = [PFQuery queryWithClassName:self.className];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error)
    {
         if (!error)
         {
             NSLog(@"Successfully Retrieved %d Objects.", (int)objects.count);    // Shows how many objects are retrieved

             for (PFObject *object in objects)
             {
                 BusinessDetailContent *businessDetailContent = [[BusinessDetailContent alloc] init];        
                 businessDetailContent.no           = object[@"ID"];
                 businessDetailContent.companyName  = object[@"Company_Name"];
                 businessDetailContent.address      = object[@"Address"];
                 businessDetailContent.tel          = object[@"Tel"];
                 businessDetailContent.email        = object[@"Email"];
                 businessDetailContent.website      = object[@"Website"];
                 businessDetailContent.details      = object[@"Details"];
                 businessDetailContent.imageName    = object[@"Image_ID"];

                 // The information here is retrieved correctly  
                 NSLog(@"BUSINESS DETAIL CONTENT - ID: %@, Company Name: %@, Address: %@, Tel: %@, Email: %@, Website: %@, Details: %@, Image_Name: %@",
                           businessDetailContent.no, businessDetailContent.companyName, businessDetailContent.address, businessDetailContent.tel,
                           businessDetailContent.email, businessDetailContent.website, businessDetailContent.details,
                           businessDetailContent.imageName);


                 [defaultBusinessArrayMutable addObject:businessDetailContent];


                 NSString *strFromInt = [NSString stringWithFormat:@"%d", tagNumber];

                 if (!([strFromInt isEqualToString:@"3"] || [strFromInt isEqualToString:@"10"]))
                     {
                         [dataArray addObject:defaultBusinessArrayMutable];
                         NSLog(@"Default Business Array Mutable Count: %i", (int)dataArray.count);
                     }
                 }
             }
         }
         else
         {
             NSLog(@"Error retrieving objects: %@ %@", error, [error userInfo]);
         }
     }];
// This line to be added
[self.tableView reloadData];

}

如果仍然存在问题，请告诉我。谢谢。