Tableview data pass through Model Class - ios

Question

I have implemented a UITableview in VC1, and I want to display some JSON data in the cell. I have implemented a Model class to pass the data to the table view.
dispatch_async(dispatch_get_main_queue(), ^{
NSURLSession*session=[NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithURL:[NSURL URLWithString:#"https://itunes.apple.com/search?term=music"] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSLog(#"%#", json);
NSArray *entryarr = [json objectForKey:#"results"];
TableClass *tc = [[TableClass alloc] init];
for (NSDictionary *appDict in entryarr) {
//setting title
NSString *str = [appDict objectForKey:#"artistName"];
[tc setTittle:str];
NSLog(#"artist Name=%#",tc.tittle);
//setting Subtitle
NSString *sub = [appDict objectForKey:#"country"];
[tc setSubtittle:sub];
NSLog(#"artist Name=%#",tc.subtittle);
//image
NSString *imageStr = [appDict objectForKey:#"artworkUrl60"];
NSURL *imageURL = [NSURL URLWithString:imageStr];
[tc setImage:imageStr];
NSData *imageData =[[NSData alloc] initWithContentsOfURL:imageURL];
//[self.imageArray addObject:imageData];
[_tableArray addObject:tc];
NSLog(#"%# name of tittle",[_tableArray objectAtIndex:0]);
}
NSLog(#"%lu %lu %lu",(unsigned long)self.tableArray.count,(unsigned long)self.tableArray.count,(unsigned long)self.tableArray.count);
[self.tableView reloadData];
}];
[dataTask resume];
});
But, while accessing it to the cell I am getting the last element in the array.
TableClass *tableclassModel = [self.tableArray objectAtIndex:indexPath.row];
cell.textLabel.text = tableclassModel.tittle;
cell.detailTextLabel.text = tableclassModel.subtittle;
cell.imageView.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:tableclassModel.image]]];
Why is it so...? How can I do it?

Answer 1

You are changing the value of same tc object again and again. Since you have declared tc object outside for loop, there will be only one tc. You are adding it to _tableArray after making the required changes in the first iteration of the loop. In the second iteration, you are changing the value of same tc object used in first iteration and adding it to _tableArray again. This will update the first object also with the new values. This goes on and finally your _tableArray will contain n number of tc objects with the same values (i.e last updated value)
Give the declaration inside the for loop
dispatch_async(dispatch_get_main_queue(), ^{
NSURLSession*session=[NSURLSession sharedSession];
NSURLSessionDataTask *dataTask = [session dataTaskWithURL:[NSURL URLWithString:#"https://itunes.apple.com/search?term=music"] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSLog(#"%#", json);
NSArray*entryarr=[json objectForKey:#"results"];
for (NSDictionary*appDict in entryarr) {
TableClass*tc=[[TableClass alloc]init];
//setting tittl
NSString*str=[appDict objectForKey:#"artistName"];
[tc setTittle:str];
NSLog(#"artist Name=%#",tc.tittle);
//setting Subtittle
NSString*sub=[appDict objectForKey:#"country"];
[tc setSubtittle:sub];
NSLog(#"artist Name=%#",tc.subtittle);
//image
NSString*imageStr=[appDict objectForKey:#"artworkUrl60"];
NSURL*imageURL=[NSURL URLWithString:imageStr];
[tc setImage:imageStr];
NSData*imageData=[[NSData alloc]initWithContentsOfURL:imageURL];
//[self.imageArray addObject:imageData];
[_tableArray addObject:tc];
NSLog(#"%# name of tittle",[_tableArray objectAtIndex:0]);
}
NSLog(#"%lu %lu %lu",(unsigned long)self.tableArray.count,(unsigned long)self.tableArray.count,(unsigned long)self.tableArray.count);
[self.tableView reloadData];
}];
[dataTask resume];
});