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In theory, cell should never be nil because my code only allows cell to be one of the identifiers above. However it still makes me nervous in terms of bad practice. Please turn on JavaScript in your browser and refresh the page to view its content. How do you create an organization that is nimble, flexible and takes a fresh view of team structure? These are the keys to creating and maintaining a successful business that will last the test of time.
- In a real application, the index could be used to pull out corresponding data from arrays or dictionaries.
- The answer is NSLayoutConstraint’s constraintsWithVisualFormat function.
- Table views are the center of many iOS applications and have many features to customize their appearance and behavior.
- 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.
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.
Updating Cell List at Runtime
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.
Calling super will give you the static cell that’s been set up in the xib file. In viewDidLoad(), configure the datasource and delegate of the table view. We need to collapse or expand the section when user taps on the header, to achieve this, let’s borrow UITapGestureRecognizer. Also we need to delegate this event to the table view to update the collapsed property. We need to add a prepare method in our CustomTableViewController file.
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.
That’s it, please refer to the source code and see the detailed implementation. Since we are not using any storyboard or XIB, how to do auto layout programmatically? The answer is NSLayoutConstraint’s constraintsWithVisualFormat function. You can even declare it as a constant, this allows the compiler to verify that it is assigned a value exactly once on each code path. If you’ve already taken the course, what follows is a quick (dare we say…swift) preview of the main things that have changed in Swift 3. Add and configure the prepare method to the CustomTableViewController file.
API Naming Guideline Changes
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 https://cryptominer.services/ 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.
How to implement collapsible table sections?
Note that there will be an error that your class doesn’t implement the required UITableViewDataSource functions. The error won’t go away until you complete Step 4 below. The key principle here is that our table view cell is now working with simple, immutable value types. Our view controller only needs to set the view data and no longer needs to care about the view internals. Unfortunately it then gets lazy and reaches into our custom table view cell and directly messes with the view.
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.
Footer navigation
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.
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.
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.
If you use Core Data you can add an NSFetchedResultsControllerDelegate. Add UISearchBarDelegate and friends and you are well on your way to a 500 line fat controller that nobody wants to touch. We know this method takes two parameters named withIdentifier and for, and we can use code completion or look at the docs to see what SQL Server Database Administrator data type is expected. Create a view controller, and drag a UITableView into the view, as shown below. I believe that renaming of Apple’s frameworks is not in the scope of swift-evolution; I think you’re supposed to file a radar. FWIW, I rely on typing `tableView` and looking at the autocompletions to find delegate methods.
We enable individuals and teams to grow their skills, accelerate their careers and create the future. Starting in Swift 3, all function parameters 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.
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.
It contains a wealth of advice on slimming a table view controller. For this post I am going to tackle just one method, cellForRowAtIndexPath, with the aim to reduce cellForAtIndexPath to just four lines. @huggie This only applies to static table views defined in interface builder.