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

Question

当我从容器中的另一个tableView中选择一行时，我试图刷新tableView（初始viewController）。

选中该行后，它将解析来自Web服务器的JSON文件，将其保存并存储在docs目录中。 主视图中的tableView应该重新加载新的JSON文件。

这是应该如何工作的：

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 （部分已被省略，因为它们没有用）

- (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];
}}

伙计们怎么了？ 告诉我，我将永远负债累累。

谢谢！

Answer 1

快速阅读代码可以使我想到一件事。

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];

我假设getDataInBackgroundWithBlock是异步的，这意味着当您到达那里的最后三行时，jsonData实际上可能不包含任何信息。

您应该在块中添加一些代码以保存数据，然后确保仅在完成所有加载后才加载新的vc。

Answer 2

可能是因为您要在后台线程上显示视图控制器。 尝试将其呈现在主运行循环上：

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