UITableView scrolling is very slow it use the network for every scrolling


Hai I am new to xcode i use a UITableView to display the vehicle number and its location. it use network for find the location. My problem is every time i scroll the table that time only it reloads the location from the net. Is it possible to load the datas for the first time and bind the table only once. Then I can scroll smoothly.Kindly advice me my code is bellow...

UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:@"MainCell"]; if(cell==nil) { cell=[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"MainCell"]; cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator; } NSString *Vehicleno=[Vehicle_No objectAtIndex:indexPath.row]; NSString *urlMapString=[NSString stringWithFormat:@"http://logix.com/logix_webservice/map.php?format=json&truckno=%@",Vehicleno]; NSURL *urlMap=[NSURL URLWithString:urlMapString]; NSData *dataMap=[NSData dataWithContentsOfURL:urlMap]; NSError *errorMap; NSDictionary *jsonMap = [NSJSONSerialization JSONObjectWithData:dataMap options:kNilOptions error:&errorMap]; NSArray *resultsMap = [jsonMap valueForKey:@"posts"]; NSArray *resMap = [resultsMap valueForKey:@"post"]; NSArray *latitudeString=[resMap valueForKey:@"latitude"]; if([latitudeString count]>0){ NSString *latOrgstring = [latitudeString objectAtIndex:0]; double latitude=[latOrgstring doubleValue]; NSArray *longitudeString=[resMap valueForKey:@"longitude"]; NSString *longOrgstring = [longitudeString objectAtIndex:0]; double longitude=[longOrgstring doubleValue]; //MAP VIEW Point MKCoordinateRegion myRegion; //Center CLLocationCoordinate2D center; center.latitude=latitude; center.longitude=longitude; //Span MKCoordinateSpan span; span.latitudeDelta=THE_SPAN; span.longitudeDelta=THE_SPAN; myRegion.center=center; myRegion.span=span; //Set our mapView [MapViewC setRegion:myRegion animated:NO]; CLLocation *someLocation=[[CLLocation alloc]initWithLatitude:latitude longitude:longitude]; CLGeocoder *geocoder = [[CLGeocoder alloc] init]; [geocoder reverseGeocodeLocation:someLocation completionHandler:^(NSArray *placemarks, NSError *error) { if ([placemarks count] > 0) { NSDictionary *dictionary = [[placemarks objectAtIndex:0] addressDictionary]; addressOutlet=[dictionary valueForKey:@"Street"]; City=[dictionary valueForKey:@"City"]; State=[dictionary valueForKey:@"State"]; if (addressOutlet!=NULL&&City!=NULL) { NSString *SubTitle=[NSString stringWithFormat:@"%@,%@,%@",addressOutlet,City,State]; cell.detailTextLabel.text=SubTitle; } else if (addressOutlet==NULL&&City!=NULL) { NSString *SubTitle=[NSString stringWithFormat:@"%@,%@",City,State]; cell.detailTextLabel.text=SubTitle; } else if (addressOutlet!=NULL&&City==NULL) { NSString *SubTitle=[NSString stringWithFormat:@"%@,%@",addressOutlet,State]; cell.detailTextLabel.text=SubTitle; } else if(addressOutlet==NULL&&City==NULL&&State!=NULL) { NSString *SubTitle=[NSString stringWithFormat:@"%@",State]; cell.detailTextLabel.text=SubTitle; } else if (addressOutlet==NULL&&City==NULL&&State==NULL) { NSString *SubTitle=[NSString stringWithFormat:@"%@",@""]; cell.detailTextLabel.text=SubTitle; } } }]; } NSUInteger row = [indexPath row]; cell.textLabel.text=[Vehicle_No objectAtIndex:row]; cell.backgroundColor=[UIColor clearColor]; return cell; }

Thanks in advance..


The main thread is used for interface operations. If you post a network request there it gets blocked, because it is waiting for the network. Post it in a background thread. Do some research on how to work with Grand Central Dispatch, blocks and Concurrency Programming. Those parts will help you out.


The good practice is to fetch your data outside from your "feeding" method. You can proceed like this:

At the top of your ViewController:

@implementation MyCustomViewController { NSMutableArray *storeArray; UITableView *myTableView; }

In your view viewDidLoad init your array, init your UITableView and run a method which is filling it:

- (void)viewDidLoad { / Init your NSMutableArray storeArray = [[NSMutableArray alloc] init]; [super viewDidLoad]; // Do any additional setup after loading the view. // Init your tableView myTableView = [[UITableView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height); myTableView.delegate = self; myTableView.datasource = self; [self addSubview:myTableView]; // Run your method [self downloadMyData]; }

Implement your code for downloading your data:

- (void)downloadMyData { // All your code here in order to download your data // And store them in your array [storeArray addObject:object]; // When you have all your data downloaded, you have to reload your tableview: [myTableView reloadData]; }

Finally, implement your UITableView protocol and fill your cell with the data in your storeArray:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:@"MainCell"]; if(cell==nil) { cell=[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"MainCell"]; cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator; // Access your data via your array data1 = [storeArray objectAtIndex:indexPath.row]; cell.dataX = data1 // ETC.... } }

Basically, some data are fetched from the web every time a cell is displayed, that's why your view appear to be very slow.


  • Objective - C to Swift : NSData with NSJSONSerialisation
  • How to add image in annotation in mkmap [duplicate]
  • Load More Table View in ios
  • google maps api get lat and lng and replace marker?
  • Image Being Saved is Not Appearing
  • Google Analytics SDK iOS10
  • Resizing UITableViewCells in iOS4 versus iOS3
  • What is the fastest way to select nearest geographical place from mysql database?
  • Tokenize python source code examples (in Python)
  • How do you open .txt file containing matrix in Matlab?
  • How do display a UIAlertView from a block on iOS?
  • Dispose not working as expected in DirectorySearcher
  • Fluid video height
  • Weird LEFT OUTER JOIN on Includes eager loading of rails 3
  • NSMutableArray instance used in a block
  • Google map in top corner left
  • didUpdatePushCredentials not get called
  • Using Sax parsing to edit and write XML in VB6
  • Trouble saving JSON data for use by multiple UIViews [duplicate]
  • Saving Changes After In-App Purchase Has Been Purchased
  • Webgrid not refreshing after delete MVC
  • Row Count Is Returning the incorrect number using RaptureXML
  • Django: Count of Group Elements
  • Sending data from AppleScript to FileMaker records
  • MySQL WHERE-condition in procedure ignored
  • Hits per day in Google Big Query
  • FormattedException instead of throw new Exception(string.Format(…)) in .NET
  • Getting Messege Twice Using IMvxMessenger
  • Change div Background jquery
  • How to get Windows thread pool to call class member function?
  • Linking SubReports Without LinkChild/LinkMaster
  • Bitwise OR returns boolean when one of operands is nil
  • XCode 8, some methods disappeared ? ex: layoutAttributesClass() -> AnyClass
  • Easiest way to encapsulate a HTML5 webpage into an android app?
  • Busy indicator not showing up in wpf window [duplicate]
  • costura.fody for a dll that references another dll
  • Observable and ngFor in Angular 2
  • How to Embed XSL into XML
  • UserPrincipal.Current returns apppool on IIS
  • Conditional In-Line CSS for IE and Others?