I have a bunch of UITableViews in my app that essentially do the same thing, so I created a protocol called Presenter and made them all conform to it. For simplicity I decided to implement UITableViewDelegate and UITableViewDataSource methods within extensions of said protocol. However, I stumbled upon multiple errors and warnings as shown below:
Adding #objc to the protocol did not help.
Now I know that making a subclass of UITableView may be easier, but I was wondering if there is a painless solution to this problem. As someone just getting acquainted with Swift, I'm trying to implement protocols as much as I can.
Here's the code:
protocol Presenter {
var viewer: Viewer { get }
}
extension Presenter where Self: UITableViewDelegate {
func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return viewer.header
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return viewer.height
}
}
extension Presenter where Self: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return viewer.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: GenericCell.identifier, for: indexPath) as! GenericCell
cell.content = viewer.viewable(at: indexPath.row)
return cell
}
}
Related
I'm updating an app of mine, and I have used this method in other areas of the app and it works, but for some reason, it's not working on a tableView.
The tableView is inside of a ViewController (CurrencyViewController)
#IBOutlet weak var tableView: UITableView!
tableView.dataSource = self
extension CurrencyViewController: UITableViewDataSource {
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 200.0
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return currencies.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "currencyCell")! as! CurrencyTableViewCell
cell.name.text = currencies[indexPath.row].currencyName
cell.name.textColor = Styles.whiteColor()
cell.symbol.text = currencies[indexPath.row].currencyCode
cell.symbol.textColor = Styles.whiteColor()
cell.backgroundColor = Styles.mainColor();
return cell
}
}
The tableView itself works, it's just not updating the height of the row.
Did something change with the update of Swift?
You don't seem to have conformed to the UITableViewDelegate ?
extension CurrencyViewController: UITableViewDataSource, UITableViewDelegate
If dataSource (and delegate) is connected in IB delete
tableView.dataSource = self
You must also adopt UITableViewDelegate in the extension, connecting the delegate is not sufficient
extension CurrencyViewController: UITableViewDataSource, UITableViewDelegate {
Question 1)
I've spent a few hours trying to figure out this problem, from what I've read those are the two functions needed to implement the UITableView but it still gives me the error in the title:
import UIKit
class UITableView: UIViewController, UITableViewDataSource,UITableViewDelegate
{
override func viewDidLoad()
{
super.viewDidLoad()
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell
{
}
}
Question 2)
The TableView is a part of a tabbed view controller that I am implementing for my app. I want my TableView controller to have entries that once pressed will open another ViewController. How can I implement something like that?
Thank you in advance
You have incorrectly set up your ViewController. Either create a UITableViewController which is just a UITableView, or add a UITableView to a UIViewController (Like you have almost done).The didSelectRowAt method will allow you to segue to a new viewController, but in my examples only if it is set up correctly in a storyboard.
UITableViewController option
class TableViewController: UITableViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 0
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return 0
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath)
// Configure the cell...
return cell
}
// MARK: - Table view delegate
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: false)
performSegue(withIdentifier: "SegueIdentifier", sender: self)
}
UIViewController option (The UITableView will need to be added through a Storyboard in this example)
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
}
// MARK: - Table view data source
func numberOfSections(in tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 0
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of rows
return 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath)
// Configure the cell...
return cell
}
// MARK: - Table view delegate
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
tableView.deselectRow(at: indexPath, animated: false)
performSegue(withIdentifier: "SegueIdentifier", sender: self)
}
Here is an example project to work from
You shouldn't be using UITableView to manage the data source. That should be the job of UITableViewController which manages data to be displayed on UITableView. The View in general should only worry about how to display the data, not manage it. See MVC design pattern by Apple.
Apple has a really nice, and complete Swift App tutorial (See Display the Data) that goes through how to set up UITableViewController with a table view you built with storyboard. You can also download and run the source project at the end of the page. I highly recommend it.
You have to to Implement This Mendatory DataSource Method
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "", for: indexPath)
return cell
}
Hope it Helps.
After some refactoring I decided to create a custom tableview that looks a bit like:
class BaseTable: UITableView, UITableViewDelegate, UITableViewDataSource {
var rowsInSection: Int { return 0}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)!
self.delegate = self
self.dataSource = self
self.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return rowsInSection
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell:UITableViewCell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
return cell
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
self.deselectRow(at: indexPath, animated: true)
}
func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
let cell: UITableViewCell = tableView.dequeueReusableCell(withIdentifier: "headerCell")!
return cell
}
func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
return 40
}
And then I subclass it like this:
class CustomTable: BaseTable{
override var rowsInSection: Int {return payArray.count }
}
This works fine, however I've noticed none of the subclassed didSelectRowAt are being called??? Can anyone help?
Well, you should follow this things:
You should split up logic from initWithCoder: to external method such as and call it in initWithFrame:, because different approaches called different init methods. Such as
func setUpTableView() {
self.delegate = self
self.dataSource = self
self.register(UITableViewCell.self, forCellReuseIdentifier: "cell")
}
For clarity in your code, you should explicitly call super method from child class methods
Otherwise, I strongly recommend you not to use this approach, better use standard UITableView in controller, and different classes, that implements protocols alongside with custom UITableViewCell's
This is bad design. The reason there are delegate and data source protocols for UITableViews is because view objects should be reusable. You're making your BaseTable class to function as a controller as well as a view.
To answer your question, are you sure it's not being called? You only have deselectRow(at:animated:) calling from tableView(didSelectRowAt:)
This question already has an answer here:
How can you provide default implementations for UIPageViewControllerDataSource?
(1 answer)
Closed 6 years ago.
I want to reuse the code below
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 3
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 5
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
return UITableViewCell()
}
I define a protocol :
protocol ConfigDetail: class, UITableViewDataSource{}
extension ConfigDetail{
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 3
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 5
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
return UITableViewCell()
}
}
but when i use the protocol with a UIViewController, it always tells me i did not conform to protocol UITableViewDataSource, or i have to add #objc before my protocol. But i have struct variables defined in my protocol, #objc may not help. Any solutions?
If you want to implement these data source methods and reuse them, just define a data source class that implements them. And then rather than implementing the delegate methods in the view controller, instantiate a data source object, keep a strong reference to it, and specify it as the data source for the table view.
For example:
class DataSource: NSObject, UITableViewDataSource {
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 3
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 5
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath)
// configure cell here
return cell
}
}
class ViewController: UITableViewController {
let dataSource = DataSource()
override func viewDidLoad() {
super.viewDidLoad()
tableView.dataSource = dataSource
}
}
Trying to conform to UITableViewDataSource and UITableViewDelegate inside a Swift UIViewController subclass.
class GameList: UIViewController {
var aTableView:UITableView = UITableView()
override func viewDidLoad() {
super.viewDidLoad()
aTableView.delegate = self
aTableView.dataSource = self
self.view.addSubview(aTableView)
//errors on both lines for not conforming
}
}
Docs say you should conform on the class line after the : but that's usually where the superclass goes. Another : doesn't work. Using a comma separated list after the superclass also doesn't work
EDIT:
Also must adopt all required methods of each protocol, which I wasn't initially doing.
You use a comma:
class GameList: UIViewController, UITableViewDelegate, UITableViewDataSource {
// ...
}
But realize that the super class must be the first item in the comma separated list.
If you do not adopt all of the required methods of the protocol there will be a compiler error. You must get all of the required methods!
As XCode6-Beta7 releases,
I noticed the protocol method of UITableViewDataSource changed a little bit and sounded the same conform to protocol error which worked fine in beta6.
These are the required methods to be implemented according to the UITableViewDataSource protocol:
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { // insert code}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int { // insert code
}
You might want to re-check the difference or re-implement the delegate method that you thought you just implement.
You must implement two require methods here:
func tableView(tableView:UITableView!, numberOfRowsInSection section:Int) -> Int {
return 10
}
func tableView(tableView:UITableView!, cellForRowAtIndexPath indexPath:NSIndexPath!) -> UITableViewCell! {
let cell: UITableViewCell = UITableViewCell(style: UITableViewCellStyle.Subtitle, reuseIdentifier: "MyTestCell")
cell.text = "Row #\(indexPath.row)"
cell.detailTextLabel.text = "Subtitle #\(indexPath.row)"
return cell
}
Also, it is important to copy all the non optional functions from the Delegate class. Cmd + Click on the UITableViewDatasource
and copy those two definitions as is.
For me in beta7, the UITableViewDatasource has
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
My implementation:
var items = ["Apple", "Pear", "Banana"]
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell:UITableViewCell = UITableViewCell(style: UITableViewCellStyle.Subtitle, reuseIdentifier: "Default")
cell.textLabel?.text = items[indexPath.row]
cell.detailTextLabel?.text = "Test"
return cell
}
Usee These methods:
There is change in Data source methods-
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
protocol UITableViewDataSource : NSObjectProtocol {
****func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
// Row display. Implementers should *always* try to reuse cells by setting each cell's reuseIdentifier and querying for available reusable cells with dequeueReusableCellWithIdentifier:
// Cell gets various attributes set automatically based on table (separators) and data source (accessory views, editing controls)
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell****
optional func numberOfSectionsInTableView(tableView: UITableView) -> Int // Default is 1 if not implemented
optional func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? // fixed font style. use custom view (UILabel) if you want something different
optional func tableView(tableView: UITableView, titleForFooterInSection section: Int) -> String?
// Editing
// Individual rows can opt out of having the -editing property set for them. If not implemented, all rows are assumed to be editable.
optional func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool
// Moving/reordering
// Allows the reorder accessory view to optionally be shown for a particular row. By default, the reorder control will be shown only if the datasource implements -tableView:moveRowAtIndexPath:toIndexPath:
optional func tableView(tableView: UITableView, canMoveRowAtIndexPath indexPath: NSIndexPath) -> Bool
// Index
optional func sectionIndexTitlesForTableView(tableView: UITableView) -> [AnyObject]! // return list of section titles to display in section index view (e.g. "ABCD...Z#")
optional func tableView(tableView: UITableView, sectionForSectionIndexTitle title: String, atIndex index: Int) -> Int // tell table which section corresponds to section title/index (e.g. "B",1))
// Data manipulation - insert and delete support
// After a row has the minus or plus button invoked (based on the UITableViewCellEditingStyle for the cell), the dataSource must commit the change
// Not called for edit actions using UITableViewRowAction - the action's handler will be invoked instead
optional func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath)
// Data manipulation - reorder / moving support
optional func tableView(tableView: UITableView, moveRowAtIndexPath sourceIndexPath: NSIndexPath, toIndexPath destinationIndexPath: NSIndexPath)
}
Ur code will works!!
This question is already answered but just want to make things a bit more Swifty.
Instead of writing protocols in UITableViewDelegate, UITableViewDataSource you can divide them using extensions this will help in organising the code. Adding protocol conformance is described in this page
for the above question, this can be confirmed to protocol using extension:
class GameList: UIViewController {
var aTableView:UITableView = UITableView()
override func viewDidLoad() {
super.viewDidLoad()
aTableView.delegate = self
aTableView.dataSource = self
self.view.addSubview(aTableView)
}
}
extension GameList: UITableViewDataSource{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return list.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "cellId", for: indexPath)
return cell
}
}
extension GameList: UITableViewDelegate{
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
print("Row Clicked at \(indexPath.row)")
}
}