ReloadData not working in my TableViewController - ios

Question

Good afternoon,
I'm trying to display the data in my UITableViewController (CarTableViewController) and at the moment the rows are being populate with the correct info and also the refreshControl is working fine (and very fast, like 1 second) but the first time I entry in my App the data is not displayed (I have to move the screen with my finger and then the data is displayed). (I have to wait like +15 seconds until it appears automatically, but sometimes is not showing).
What can I do in order to display the data automatically and fast?
I tried to move the reloadData into every method and it's always the same and I don't know what else to do...! I will be much appreciated if you can help me with that.
CarTableViewController.m
#import "CarTableViewController.h"
#import "CarTableViewCell.h"
#import "CarTableViewController.h"
#import "CarDetailViewController.h"
#import <SDWebImage/UIImageView+WebCache.h>
#implementation CarTableViewController
#synthesize carMakes = _carMakes;
#synthesize carModels = _carModels;
#synthesize carImages = _carImages;
#synthesize likes = _likes;
#synthesize comments = _comments;
#synthesize username = _username;
#synthesize refuser = _refuser;
#synthesize profileImage = _profileImage;
- (void)viewDidLoad
{
[super viewDidLoad];
[self fetchJson];
[self.tableView reloadData];
// Initialize the refresh control.
self.refreshControl = [[UIRefreshControl alloc] init];
self.refreshControl.backgroundColor = [UIColor blackColor];
self.refreshControl.tintColor = [UIColor whiteColor];
[self.refreshControl addTarget:self
action:#selector(fetchJson)
forControlEvents:UIControlEventValueChanged];
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [_jsonArray count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"carTableCell";
CarTableViewCell *cell = [tableView
dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[CarTableViewCell alloc]
initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
}
// Configure the cell...
cell.makeLabel.text = [[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"id"];
cell.likes.text = [[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"likes"];
cell.comments.text = [[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"comments"];
cell.username.text = [[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"username"];
cell.refuser.text = [[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"user_ref"];
cell.modelLabel.text = [[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"user"];
NSURL * imageURL = [NSURL URLWithString:[[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"imagen"]];
[cell.carImage setImageWithURL:imageURL
placeholderImage:[UIImage imageNamed:#"placeholder.png"]
options:SDWebImageRefreshCached];
NSURL * imageURL2 = [NSURL URLWithString:[[_jsonArray objectAtIndex:indexPath.row] valueForKey:#"image"]];
[cell.profileImage setImageWithURL:imageURL2
placeholderImage:[UIImage imageNamed:#"image"]
options:SDWebImageRefreshCached];
return cell;
}
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if ([[segue identifier] isEqualToString:#"ShowCarDetails"])
{
CarDetailViewController *detailViewController = [segue destinationViewController];
NSIndexPath *myIndexPath = [self.tableView indexPathForSelectedRow];
detailViewController.carDetailModel = [[NSArray alloc]
initWithObjects:
[[_jsonArray objectAtIndex:[myIndexPath row]] valueForKey:#"date"],
[[_jsonArray objectAtIndex:[myIndexPath row]] valueForKey:#"id"],
[[_jsonArray objectAtIndex:[myIndexPath row]] valueForKey:#"imagen"],
nil];
}
}
-(void)fetchJson {
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
NSString * urlString = [NSString stringWithFormat:#"http://mywebsite.com/service.php"];
NSURL * url = [NSURL URLWithString:urlString];
NSData * data = [NSData dataWithContentsOfURL:url];
self.carModels = [[NSMutableArray alloc] init];
self.carMakes = [[NSMutableArray alloc] init];
self.carImages = [[NSMutableArray alloc] init];
self.likes = [[NSMutableArray alloc] init];
self.comments = [[NSMutableArray alloc] init];
#try
{
NSError *error;
[_jsonArray removeAllObjects];
_jsonArray = [NSJSONSerialization
JSONObjectWithData:data
options:NSJSONReadingMutableContainers|NSJSONReadingMutableLeaves
error:&error];
for(int i=0;i<_jsonArray.count;i++)
{
NSDictionary * jsonObject = [_jsonArray objectAtIndex:i];
NSString* imagen = [jsonObject objectForKey:#"imagen"];
[_carImages addObject:imagen];
NSDictionary * jsonObject2 = [_jsonArray objectAtIndex:i];
NSString* user = [jsonObject2 objectForKey:#"user"];
[_carMakes addObject:user];
NSDictionary * jsonObject3 = [_jsonArray objectAtIndex:i];
NSString* date = [jsonObject3 objectForKey:#"date"];
[_carModels addObject:date];
}
}
#catch (NSException * e)
{
NSLog(#"Exception: %#", e);
}
#finally
{
[self.tableView reloadData];
[self.refreshControl endRefreshing];
}
}
);
}
#end
CarTableViewController.h
#import <UIKit/UIKit.h>
#interface CarTableViewController : UITableViewController
#property (nonatomic, strong) IBOutlet UITableView *tableView;
#property (nonatomic, strong) NSMutableArray *carImages;
#property (nonatomic, strong) NSMutableArray *carMakes;
#property (nonatomic, strong) NSMutableArray *carModels;
#property (nonatomic, strong) NSMutableArray *likes;
#property (nonatomic, strong) NSMutableArray *comments;
#property (nonatomic, strong) NSMutableArray *username;
#property (nonatomic, strong) NSMutableArray *refuser;
#property (nonatomic, strong) NSMutableArray *profileImage;
#property (nonatomic, strong) NSMutableArray *jsonArray;
#end
Thanks in advance.

Answer 1

Your problem is in fetchJson. You're calling reloadData on a background thread, which has unpredictable results. You need to make sure that you call any UI methods on the main thread.
Replace your code with the following:
- (void)fetchJson
{
self.carModels = [[NSMutableArray alloc] init];
self.carMakes = [[NSMutableArray alloc] init];
self.carImages = [[NSMutableArray alloc] init];
self.likes = [[NSMutableArray alloc] init];
self.comments = [[NSMutableArray alloc] init];
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(queue, ^{
NSString * urlString = [NSString stringWithFormat:#"http://mywebsite.com/service.php"];
NSURL * url = [NSURL URLWithString:urlString];
NSData * data = [NSData dataWithContentsOfURL:url];
NSError *error;
_jsonArray = [NSJSONSerialization
JSONObjectWithData:data
options:NSJSONReadingMutableContainers | NSJSONReadingMutableLeaves
error:&error];
for (NSDictionary * jsonObject in _jsonArray)
{
NSString* imagen = [jsonObject objectForKey:#"imagen"];
[_carImages addObject:imagen];
NSDictionary * jsonObject2 = [_jsonArray objectAtIndex:i];
NSString* user = [jsonObject2 objectForKey:#"user"];
[_carMakes addObject:user];
NSDictionary * jsonObject3 = [_jsonArray objectAtIndex:i];
NSString* date = [jsonObject3 objectForKey:#"date"];
[_carModels addObject:date];
}
dispatch_async(dispatch_get_main_queue(), ^{
[self.tableView reloadData];
[self.refreshControl endRefreshing];
});
);
}