Load all data from parse before displaying table - ios

Question

I'm currently trying to populate a tableView with information stored on my Parse server (username, description, profile picture)
Currently... When I open the tableview I do not get any information showing, but if I click back and re open the table, all of my information shows and I'm unsure why that is.
A first get all information needed from Parse and store them into arrays like so:
let query = PFQuery(className: institutionTitle)
query.findObjectsInBackground {
(objects, error) in
if error == nil {
// The find succeeded.
// Do something with the found objects
if let objects = objects {
for object in objects {
self.postGrabber.append(object)
self.pSenderUsername.append(object["sender"] as! String)
self.pPostBody.append(object["textPost"] as! String)
}
}
} else {
// Log details of the failure
print("Error: \(error!)")
}
}
I'm currently using both the viewDidLoad() and viewWillAppear() to reloadData()
I then set the delegate and datasource of the table view in the viewDidLoad() function.
I then use the cellForRowAtIndexPath method to set up each cell on the table:
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell: UniversityFeedCellTableViewCell = tableView.dequeueReusableCell(withIdentifier: "postCell", for: indexPath) as! UniversityFeedCellTableViewCell
cell.sender.text = pSenderUsername[indexPath.section]
cell.senderPost.text = pPostBody[indexPath.section]
cell.profilePicture.layer.cornerRadius = cell.profilePicture.frame.size.width / 2
cell.profilePicture.layer.borderColor = UIColor.orange.cgColor
cell.backgroundColor = UIColor.white
return cell
}
I'm looking for some information on how I would make the user wait until all data has successfully loaded and has been populated. Would appreciate some help.
Thanks in advance and feel free to request more information from myself.

Answer 1

You need to reload data in table view after you have fetched all from your server... Something like this should do the trick:
let query = PFQuery(className: institutionTitle)
query.findObjectsInBackground {
(objects, error) in
if error == nil {
// The find succeeded.
// Do something with the found objects
if let objects = objects {
for object in objects {
self.postGrabber.append(object)
self.pSenderUsername.append(object["sender"] as! String)
self.pPostBody.append(object["textPost"] as! String)
}
dispatch_async(dispatch_get_main_queue(), {
self.tableView.reloadData() // Add this line and it should work
})
}
} else {
// Log details of the failure
print("Error: \(error!)")
}
}
If you want to load your data each time your view controller appears then do it in viewWillAppear(), otherWise, if you need to load data only first time, then in viewDidLoad()

Answer 2

You need to set callback method when u fetch json from server and then if result fetch you have to call reload method and mean while you can set indicator. Callback method done with fetch its will reload data
If u need some code example then i can mention the code hear

Answer 3

first you need to add this callback block in you .h file //Callback blocks
void (^successCallback)(id response);
void (^failCallback)(NSError *error);
+(BOOL)CallService3:(NSString*)serviceName postData:(NSString*)params qString:(NSString*)QueryStr callBackBlock:(void (^)(id response))responeBlock;
in you implementation file mean .m file create method for calling web api or web service
+(BOOL)CallService3:(NSString*)serviceName postData:(NSString*)params qString:(NSString*)QueryStr callBackBlock:(void (^)(id response))responeBlock{
NSString *jsonString =params;//if you have dictionary then [params JSONRepresentation];
NSString *post = [NSString stringWithFormat:#"json=%#", jsonString];
NSData *postData = [post dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:NO];
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration defaultSessionConfiguration];
sessionConfiguration.HTTPAdditionalHeaders = #{
#"api-key" : #"API_KEY"
};
NSURLSession *session = [NSURLSession sessionWithConfiguration:sessionConfiguration];
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:#"%#%#",baseURLS,serviceName]];
NSLog(#"url %#",[url absoluteString]);
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPMethod = #"GET";
NSURLSessionDataTask *postDataTask = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary* jsonObject = [NSJSONSerialization JSONObjectWithData:data
options:kNilOptions
error:&error];
responeBlock(jsonObject);
}];
[postDataTask resume];
return TRUE;
}
After creating this method you have to call this for callback function
-(void)callWebApi{
//here you can call indicator if you need this class i can share with you
// [self startActivityIndicatorInView:self.view withMessage:#"please wait"];
[Connection CallService3:WebApi_Category postData:jsonstring qString:str callBackBlock:^(id response){
// NSLog(#"param .. %#",response);
// NSLog(#"%#",[response allKeys]);
//NSLog(#"param .. %#",response);
jsonArray=[[NSDictionary alloc]initWithDictionary:response];
dispatch_async(dispatch_get_main_queue(), ^(void){
//stop indicator here
// [self stopActivityIndicatorInView:self.view];
[self call_your_method_populating_table:[jsonArray objectForKey:kModel]];
//now call reload tableview
[_tableview reloadData];
});
}];
}