调用[tableView reloadData]时，TableView无法重新加载

Question

I'm trying to get my tableView (initial viewController) to refresh when I select a row from another tableView in a container.

When the row is selected, it parses a JSON file from a web server, saves it and store it in the docs directory. The tableView from the main view should be reloading with the new JSON file.

This is how it should be working:

OpenWorkViewController.m

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath (NSIndexPath *)indexPath{

PFQuery *query = [PFQuery queryWithClassName:@"Travaux"];
[query whereKey:@"profID" equalTo:@"EAPFfaGSOE"];
[query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
    if (!error) {

        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"form.json"];

        for (PFObject *object in objects) {

            PFFile *file = object[@"json"];

            [file getDataInBackgroundWithBlock:^(NSData *jsonData, NSError *error) {
                if (!error) {
                    self.jsonData = jsonData;
                }
            }];
        }

        [self.jsonData writeToFile:appFile atomically:YES];
        ViewController *vc = [[ViewController alloc] initWithNibName:nil bundle:nil];
        [vc viewDidLoad];

    } else {
        // Log details of the failure
        NSLog(@"Error: %@ %@", error, [error userInfo]);
    }
}];}

ViewController.h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController <UITableViewDataSource, UITableViewDelegate>
    {
    UITableView *form;
    }

@property CGFloat shortQuestion;
@property CGFloat choiceQuestion;
@property CGFloat multipleQuestion;

@property (strong, nonatomic) NSMutableArray *numbersCell;
@property (strong, nonatomic) NSMutableArray *questionType;
@property (strong, nonatomic) NSMutableArray *inputsArray;
@property (strong, nonatomic) NSMutableDictionary *inputsDict;
@property (strong, nonatomic) NSString *indexAnswer;
@property (strong, nonatomic) NSString *formData;

-(void)readQuestions:(NSString *)path;

@end

ViewController.m (parts have been omitted, bc they are useless)

- (void)viewDidLoad {

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:@"form.json"];
//NSLog(@"%s  === %@", __PRETTY_FUNCTION__, filePath);
self.formData = filePath;
[self readQuestions:filePath];

UIView *shortView = [[[NSBundle mainBundle] loadNibNamed:@"ECFormShortQuestion" owner:self options:nil] objectAtIndex:0];
self.shortQuestion = [shortView bounds].size.height;

UIView *choiceView = [[[NSBundle mainBundle] loadNibNamed:@"ECFormChoiceQuestion" owner:self options:nil] objectAtIndex:0];
self.choiceQuestion = [choiceView bounds].size.height;

UIView *multipleView = [[[NSBundle mainBundle] loadNibNamed:@"ECFormMultipleQuestion" owner:self options:nil] objectAtIndex:0];
self.multipleQuestion = [multipleView bounds].size.height;

self.automaticallyAdjustsScrollViewInsets = NO; //important


[super viewDidLoad];}

-(void)readQuestions:(NSString *)path
    {
//NSString *filePath =[[NSBundle mainBundle] pathForResource:@"input" ofType:@"json"];

self.numbersCell = [[NSMutableArray alloc] init];
self.questionType = [[NSMutableArray alloc] init];
self.inputsArray = [[NSMutableArray alloc] init];
self.inputsDict = [[NSMutableDictionary alloc] init];

if ([path length])
{
    NSError *readError;
    NSData *questionsData = [[NSData alloc] initWithContentsOfFile:path options:NSMappedRead error:&readError];


    if (!readError)
    {
        NSError *parseError;
        NSMutableDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:questionsData options:NSJSONReadingMutableContainers error:&parseError];

        if (!parseError && dictionary)
        {
            NSMutableDictionary *questionsDictionary = [dictionary objectForKey:@"questions"];
            int number= -1; // Question number
            //NSLog(@"%@",questionsDictionary);
            for (NSMutableDictionary *singleQuestion in questionsDictionary)
            {
                NSString *questionType = [singleQuestion objectForKey:@"type"];
                NSString *questionTitle = [singleQuestion objectForKey:@"title"];
                NSMutableDictionary *inputs = [singleQuestion objectForKey:@"inputs"];
                NSMutableArray *a = [NSMutableArray array];

                for (NSDictionary *d in inputs)
                {
                    NSArray *arr = [d allKeys];
                    NSString *theKey = [arr lastObject];
                    [a addObject:theKey];
                }

                self.indexAnswer = [NSString stringWithFormat:@"%d", ++number];

                for (int i = 1;i<=[a count];i++)
                {
                    [self.inputsDict setObject:a forKey:self.indexAnswer];

                }

                [self.numbersCell addObject:questionTitle];
                [self.questionType addObject:questionType];

            }

        }
    }
    form=[[UITableView alloc]init];
    form.frame = CGRectMake(0,64,700,704);
    form.dataSource=self;
    form.delegate=self;
    form.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;

    [self.view addSubview:form];

    [form reloadData];
}}

What is wrong guys?! Tell me, and I'll be forever in debt.

Thanks!

Answer 1

One thing jumps out to me in a quick read through the code.

for (PFObject *object in objects) {

        PFFile *file = object[@"json"];

        [file getDataInBackgroundWithBlock:^(NSData *jsonData, NSError *error) {
            if (!error) {
                self.jsonData = jsonData;
            }
        }];
    }

    [self.jsonData writeToFile:appFile atomically:YES];
    ViewController *vc = [[ViewController alloc] initWithNibName:nil bundle:nil];
    [vc viewDidLoad];

I assume that getDataInBackgroundWithBlock is asynchronous, which means that when you get to the last three lines there, jsonData may not actually contain any information.

You should add some code in the block to save the data, and then make sure that you only load the new vc after you have finished loading everything.

Answer 2

It is probably because you are presenting the view controller on the background thread. Try presenting it on the main run loop:

[self.jsonData writeToFile:appFile atomically:YES];
dispatch_async(dispatch_get_main_queue(), ^{
    ViewController *vc = [[ViewController alloc] initWithNibName:nil bundle:nil];
    [vc viewDidLoad];
});