self tableView reloadData not working in Swift

Question

I m attempting to learn Swift  amp  the basics of iOS dev at the same time  so bear with me  I ve got a TableViewController that is firstly parsing a local JSON file and rendering it s very simple data into TableViewCell and SectionHeaderViews  Within the same TableViewController  I m making a call to a JSON endpoint  which is returning data  which I am then setting to variables so I can access what I actually want to get at  the API structure is less than desirable   So  I finally set the proper data to be self tableData and then call self tableView reloadData   but nothing happens  What gives   import UIKit  class BusinessTableViewController  UITableViewController        var data  NSMutableData   NSMutableData       var tableData  NSArray   NSArray         lazy var Business  NSArray             let pathTCT   NSBundle mainBundle   pathForResource  TCT   ofType   json           let data   NSData dataWithContentsOfFile pathTCT  options  nil  error  nil          return NSJSONSerialization JSONObjectWithData data  options  nil  error  nil  as NSArray                  override func viewDidLoad             super viewDidLoad            navigationItem titleView   UIImageView image  UIImage named   growler             tableView registerClass BeerTableViewCell self  forCellReuseIdentifier   cell           tableView separatorStyle    None          fetchKimono              override func numberOfSectionsInTableView tableView  UITableView   - gt  Int             return Business count         return 1            override func tableView tableView  UITableView   numberOfRowsInSection section  Int  - gt  Int           let biz   Business section  as NSDictionary         let results   biz  results   as NSDictionary         let beers   results  collection1   as NSArray         return beers count            override func tableView tableView  UITableView   cellForRowAtIndexPath indexPath  NSIndexPath   - gt  UITableViewCell            let cell   tableView  dequeueReusableCellWithIdentifier  cell   forIndexPath  indexPath   as BeerTableViewCell         if let path   indexPath               let biz   Business path section  as NSDictionary             let results   biz  results   as NSDictionary             let beers   results  collection1   as NSArray             let beer   beers path row  as NSDictionary              cell titleLabel text   beer  BeerName   as String                    return cell            override func tableView tableView  UITableView   titleForHeaderInSection section  Int  - gt  String            let biz   Business section  as NSDictionary         return biz  name   as String            override func tableView tableView  UITableView   viewForHeaderInSection section  Int  - gt  UIView            let biz   Business section  as NSDictionary         let view   LocationHeaderView           view titleLabel text    biz  name   as String  uppercaseString         return view            override func tableView tableView  UITableView   heightForHeaderInSection section  Int  - gt  CGFloat           return 45            func fetchKimono             var urlPath    names have been changed to protect the innocent          var url  NSURL   NSURL string  urlPath          var request  NSURLRequest   NSURLRequest URL  url          var connection  NSURLConnection   NSURLConnection request  request  delegate  self  startImmediately  false           connection start              func connection didReceiveResponse  NSURLConnection   didReceiveResponse response  NSURLResponse                Recieved a new request  clear out the data object         self data   NSMutableData              func connection connection  NSURLConnection   didReceiveData data  NSData                Append the recieved chunk of data to our data object         self data appendData data             func connectionDidFinishLoading connection  NSURLConnection                Request complete  self data should now hold the resulting info            Convert the retrieved data in to an object through JSON deserialization         var err  NSError         var jsonResult  NSDictionary   NSJSONSerialization JSONObjectWithData data  options     NSJSONReadingOptions MutableContainers  error  nil  as NSDictionary         var results  NSDictionary   jsonResult  results   as NSDictionary         var collection  NSArray   results  collection1   as NSArray         if jsonResult count gt 0  amp  amp  collection count gt 0               var results  NSArray   collection as NSArray             self tableData   results             self tableView reloadData

User · Answer

Try it  tableView reloadSections IndexSet integersIn  0   0   with   automatic  It helped me

User · Answer

I was also facing the same issue  what I did wrong was that I d forgot to add   tableView delegate   self     tableView dataSource   self   in the viewDidLoad      method  This could be one reason of self tableView reloadData   not working

User · Answer

You ll need to reload the table on the UI thread via     swift 2 3 dispatch async dispatch get main queue         - gt  Void in     self tableView reloadData         swift 5 DispatchQueue main async      self tableView reloadData       Follow up  An easier alternative to the connection start   approach is to instead use NSURLConnection sendAsynchronousRequest         NSOperationQueue mainQueue   is the main thread NSURLConnection sendAsynchronousRequest NSURLRequest URL  url   queue  NSOperationQueue mainQueue       response  data  error  - gt  Void in       check error     var jsonError  NSError      let json  AnyObject    NSJSONSerialization JSONObjectWithData data  options  NSJSONReadingOptions allZeros  error   amp jsonError        check jsonError     self collectionView  reloadData       This doesn t allow you the flexibility of tracking the bytes though  for example you might want to calculate the progress of the download via bytesDownloaded bytesNeeded

User · Answer

If your connection is in background thread then you should update UI in main thread like this  self tblMainTable performSelectorOnMainThread Selector  reloadData    withObject  nil  waitUntilDone  true    As I have mentioned here  Swift 4   self tblMainTable performSelector onMainThread   selector UICollectionView reloadData   with  nil  waitUntilDone  true

User · Answer

You have just to enter   First a IBOutlet    IBOutlet var appsTableView   UITableView   Then in a Action func   self appsTableView reloadData

User · Answer

So  the issue was that I was trying to inappropriately use  lazy  which caused my Business variable to essentially be a constant  and thusly uneditable  Also  instead of loading the local json  I m now loading only the data returned from the API   import UIKit  class BusinessTableViewController  UITableViewController        var data  NSMutableData   NSMutableData       var Business  NSMutableArray   NSMutableArray        override func viewDidLoad             super viewDidLoad            navigationItem titleView   UIImageView image  UIImage named   growler             tableView registerClass BeerTableViewCell self  forCellReuseIdentifier   cell           tableView separatorStyle    None          fetchKimono              override func numberOfSectionsInTableView tableView  UITableView   - gt  Int           return Business count            override func tableView tableView  UITableView   numberOfRowsInSection section  Int  - gt  Int           if  Business count  gt  0                let biz   Business section  as NSDictionary             let beers   biz  results   as NSArray             return beers count           else               return 0                       override func tableView tableView  UITableView   cellForRowAtIndexPath indexPath  NSIndexPath   - gt  UITableViewCell            let cell   tableView  dequeueReusableCellWithIdentifier  cell   forIndexPath  indexPath   as BeerTableViewCell         if let path   indexPath               let biz   Business path section  as NSDictionary             let beers   biz  results   as NSArray             let beer   beers path row  as NSDictionary              cell titleLabel text   beer  BeerName   as String           else               cell titleLabel text    Loading                     return cell            override func tableView tableView  UITableView   viewForHeaderInSection section  Int  - gt  UIView            let view   LocationHeaderView           let biz   Business section  as NSDictionary         if  Business count  gt  0                let count      Business count               view titleLabel text    biz  name   as String  uppercaseString                   return view            override func tableView tableView  UITableView   heightForHeaderInSection section  Int  - gt  CGFloat           return 45            func fetchKimono             var urlPath    names have been removed to protect the innocent          var url  NSURL   NSURL string  urlPath          var request  NSURLRequest   NSURLRequest URL  url          var connection  NSURLConnection   NSURLConnection request  request  delegate  self  startImmediately  false           connection start              func connection didReceiveResponse  NSURLConnection   didReceiveResponse response  NSURLResponse                Recieved a new request  clear out the data object         self data   NSMutableData              func connection connection  NSURLConnection   didReceiveData data  NSData                Append the recieved chunk of data to our data object         self data appendData data             func connectionDidFinishLoading connection  NSURLConnection                Request complete  self data should now hold the resulting info            Convert the retrieved data in to an object through JSON deserialization         var err  NSError         var jsonResult  NSDictionary   NSJSONSerialization JSONObjectWithData data  options  NSJSONReadingOptions MutableContainers  error  nil  as NSDictionary         var results  NSDictionary   jsonResult  results   as NSDictionary         var collection  NSArray   results  collection1   as NSArray         if jsonResult count gt 0  amp  amp  collection count gt 0               Business   jsonResult             tableView reloadData                       Swift Docs on  lazy       You must always declare a lazy property as a variable  with the var keyword   because its initial value may not be retrieved until after instance initialization completes  Constant properties must always have a value before initialization completes  and therefore cannot be declared as lazy

User · Answer

In my case the table was updated correctly  but setNeedDisplay   was not called for the image so I mistakenly thought that the data was not reloaded

User · Answer

Beside the obvious reloadData from UI Main Thread  whatever Apple calls it   in my case  I had forgotten to also update the SECTIONS info  Therefor it did not detect any new sections

User · Answer

You must reload your TableView in main thread only  Otherwise your app will be crashed or will be updated after some time  For every UI update it is recommended to use main thread      To update UI only this below code is enough   If you want to do changes in UI use this DispatchQueue main async execute          Update UI     self tableView reloadData    Your tableView here       Perform some task and update UI immediately  DispatchQueue global qos   userInitiated  async            Call your function here     DispatchQueue main async                Update UI         self tableView reloadData                To call or execute function after some time and update UI DispatchQueue main asyncAfter deadline   now     5 0          Here call your function       If you want to do changes in UI use this     DispatchQueue main async execute              Update UI         self tableView reloadData

User · Answer

All the calls to UI should be asynchronous  anything you change on the UI like updating table or changing text label should be done from main thread  using DispatchQueue main will add your operation to the queue on the main thread    Swift 4  DispatchQueue main async      self tableView reloadData

[ios] self.tableView.reloadData() not working in Swift

Examples related to ios

Examples related to objective-c

Examples related to json

Examples related to uitableview

Examples related to swift