23 Apr

Apple Developer Documentation

For example, consider this UITableViewDataSource method. What was a little surprising, however, was the fact that Apple decided to include a major overhaul of API naming and common syntax. Set the text of the Label within the viewDidLoad method. Create an Instance Variable to hold the index data that will be passed from the CustomTableViewController. To do this we will make ViewControllerA a delegate of ViewControllerB. This allows ViewControllerB to send a message back to ViewControllerA enabling us to send data back.

cellforrowatindexpath swift 3

FYI. Assuming your table view is in storyboard you can hook up the data source and delegate inside storyboard instead of code. In iOS, it is common to use multiple cells of different classes within a tableView. This can become quite hairy since our cellForRowAtIndexPath can quickly become bloated.

Updating Cell List at Runtime

To pass data back from ViewControllerB to ViewControllerA you need to use Protocols and Delegates or Blocks, the latter can be used as a loosely coupled mechanism for callbacks. This question seems to be very popular here on Stack Overflow so I thought I would try and give a better answer to help out people starting in the world of iOS like me. Short version is, we couldn’t find any obvious way to translate delegates, so we punted on it. I’m using an array of struct Vehicle for the data for the TableView.

We enable individuals and teams to grow their skills, accelerate their careers and create the future. Starting in Swift 3, all function parameters Your ultimate guide to Heroku custom domain name need to be named. Many core API method names have changed to better reflect a shift away from the old Objective-C way of naming things.

Declare that the class implements the table view datasource and delegate protocols. Look for the class declaration at the top of your Swift or Objective-C file. Add UITableViewDataSource and UITableViewDelegate after UIViewController.

For ViewControllerA to be a delegate of ViewControllerB it must conform to ViewControllerB’s protocol which we have to specify. This tells ViewControllerA which methods it must implement. The UITableViewController is a go-to class for iOS developers but seems especially prone to code bloat. Consider that right out of the box it is both a UITableViewDataSource and UITableViewDelegate.

Using Cell List within Table View’s Data Source

It’s been a good run, but Swift 3 has started the process of renaming many of those methods to versions without the NS in front. For example, NSIndexPath is now just IndexPath, and NSFileManager is now FileManager. Then, in the Attribute Inspector, set the Identifier of the custom cell. Select the UITableViewCell in Storyboard and type in the name of the custom cell in the Identity Inspector. In ViewControllerB we call a message on the delegate when we pop the view controller.

The sections below cover basic as well as more custom table views. Passing data forward to a view controller from another view controller. You would use this method if you wanted to pass an object/value from one view controller to another view controller that you may be https://topbitcoinnews.org/ pushing on to a navigation stack. In case of a custom table view cell the cell can be forced casted to the custom type. There are many table view methods, but the only required methods are to set the number of rows for the table view and to return the cell for each row.

The prepare method is called right before any segue happens from that ViewController. This will give us the opportunity to pass any data we need to the DetailViewController right before the segue happens. Let say in any case xib file missing or something then this method will return an empty cell as the UITableViewCell. If that so user will see nothing and there is no way us as developer to get notified about it.

cellforrowatindexpath swift 3

@Edwurtle is right you surely forget to connect your table view to your view controller. In the storyboard you should ctrl + drag from your table view to the hello icon at the top of your view controller. We need to convert from our task object to the view data used by the cell. For example our task object could have an NSDate object but our view data needs a formatted and localised string to display. We don’t want that data transformation code cluttering our view controller. Table views are the center of many iOS applications and have many features to customize their appearance and behavior.

cellForRowAtIndexPath in Four Lines

If we didn’t return empty cell and let application to crash in any case xib is missing at least we can get notified that something is wrong on our application. Create outlets to the custom cell class for any view you want to configure in code. By doing so, we implicitly linked the index path to the cell class. The beauty is simply changing the location of the enum within our cell List will directly correlate with the index path shown in our tableView. There won’t be a need to change the cellForRow if it already handles that cell properly. If you just want to return one of the two possible prototype cells then you don’t need to cast at all.

If we need to add another phone cell, all we need to do is update our cell List. For Swift 3.0, we are migrating in migrate-to-swift-3.0 branch, eventually it will be merged back to master branch.

Control-drag from the view to the implementation file to create an outlet to the UITableView. Before pushing viewControllerB to navigation stack we need to tell ViewControllerB that ViewControllerA is its delegate, otherwise we will get an error. NS-prefixed classes are immediately recognizable to any iOS developer. They are a historical artifact from way back in the ’90s when Apple acquired NeXT and the NeXTSTEP operating system, and thus the prefix NS made its way into Apple’s frameworks.

  • Add UITableViewDataSource and UITableViewDelegate after UIViewController.
  • We need to add a prepare method in our CustomTableViewController file.
  • In the storyboard you should ctrl + drag from your table view to the hello icon at the top of your view controller.
  • These are the keys to creating and maintaining a successful business that will last the test of time.

This is because we haven’t passed any data to the DetailViewController yet. In this demo, we will simply display the index value in the label of the DetailViewController to prove that we know which cell was tapped. In a real application, the index could be used to pull out corresponding data from arrays or dictionaries. Create an outlet from the label in your prototype cell to your Custom Cell file.

Make App Pie

We have all done it but this is straying from the path of lean and clean view controllers which leads to pain and we all know where that ends up. When a user taps a cell in your table view, we will often want to navigate to another view controller that contains information related to the cell that was tapped. In order to do this, we will need to figure out which cell was tapped, and then pass the relevant data from that cell to the next view controller. In practice, a UITableViewCell is rarely appropriate for your table views. Instead, you’ll often need to create a custom cell with different subviews and custom highlight and selection effects. To create and use a custom cell, follow the steps below.

[Answer]-Correct implementation of cellForRowAtIndexPath in Swift 2.0-swift

When I try each of the suggestions to either silence the warning with @nonobjc or make it a private function the table no longer loads. Swift-evolution; I think you’re supposed to file a radar. ViewForHeaderInSection Allows the configuration of a custom view as the header for the section. Should return YES if the specified row can be deleted or added. However, I also don’t like creating an if let statement a thousand times.

I have seen developers directly use the indexpath to determine which cell to dequeue. Hardcoding the indexpaths to cells not only makes the code harder to reader, but it also makes it harder to change. A solution I have found is to use a cellList to manage all of this. If you have not seen it I recommend spending an hour to watch the great talk Andy Matuschak gave at NSSpain on refactoring view controllers.