I have a delegation/initialization problem I can't seem to solve. Basically I have a storyboard with a few View controllers. Inside the storyboard there is this "View controller" which consists of a UITableview that I have connected with a DeviceListViewController class so that it populates the information. In here I have declared the following protocol:
protocol DeviceListViewControllerDelegate: UIAlertViewDelegate {
var connectionMode:ConnectionMode { get }
func connectPeripheral(peripheral:CBPeripheral, mode:ConnectionMode)
func stopScan()
func startScan()
}
and inside the class itself I have a init method like this (which is probably wrong but I didn't know what else I could do at this point):
convenience init(aDelegate: DeviceListViewControllerDelegate) {
self.init()
self.delegate = aDelegate
}
Then there is this second class that is not attached to any view controller called BLEMainViewController. It should be a singleton handling all the bluetooth actions. This means I should be able to delegate some stuff between DevicelistViewController and BLEMainViewController.
In the BLEMainViewController I have inherited the DeviceListViewControllerDelegate:
class BLEMainViewController: NSObject, DeviceListViewControllerDelegate {
var deviceListViewController:DeviceListViewController!
var delegate: BLEMainViewControllerDelegate?
static let sharedInstance = BLEMainViewController()
}
override init() {
super.init()
// deviceListViewController.delegate = self
deviceListViewController = DeviceListViewController(aDelegate: self)
}
The problem is that BLEMainViewController is not attached to any View Controller (and it shouldn't IMO) but it needs to be initialized as a singleton in order to handle all the BLE actions. Can anyone point me in the right direction (with an example preferably) on how to work around this?
I think you simply used wrong code architecture.
The BLEManager is a shared-instance, you can call it from everywhere, set it properties, and call its methods.
Its can delegate your view-controller with any predefine events you will add to its protocol and provide proper implementation
Here is some code, hope it helps
protocol BLEManagerDelegate{
func bleManagerDidStartScan(manager : BLEManager)
}
class BLEManager: NSObject {
static let sharedInstance = BLEManager()
var delegate: BLEManagerDelegate?
var devices : [AnyObject] = []
func startScan(){
delegate?.bleManagerDidStartScan(self)
//do what ever
}
func stopScan(){
}
}
Related
I have a AAATableViewController with tableView.
And I have a separate swift singleton file.
In a singleton, I have a function with some logic and in this logic,
I have
DispatchQueue.main.async {
self.tableView.reloadData()
}
but it shows an error because there is no tableview in a singleton class.
How can I reload AAATableViewController's tableview inside singleton using delegate and protocol?
I read some articles with delegate , but they are all between viewcontrollers, and couldn't figure out.
I am making some assumptions about the structure of your code, but I think you're going to want something like this:
protocol ReloadDelegate: AnyObject {
func reloadTable()
}
struct Singleton {
weak var reloadDelegate: ReloadDelegate?
static var shared = Singleton()
func doSomething() {
DispatchQueue.main.async {
self.reloadDelegate?.reloadTable()
}
}
}
class TableViewController: UITableViewController, ReloadDelegate {
override func viewDidLoad() {
super.viewDidLoad()
Singleton.shared.reloadDelegate = self
}
func reloadTable() {
self.tableView.reloadData()
}
}
When you create the TableViewController, you'll need to set the Singleton's reload delegate to the TableViewController. Now the Singleton knows about the TableViewController and can tell it to reload.
I have a main view titled NoteTakerViewController. I have a weatherGetterController class with a protocol that returns 5 days of weather with a protocol function called getMyWeather. However the protocol function is not being called that returns the weather data to NoteTakerViewController. I am certain I have everything set up correctly with the delegates but perhaps I do not.
This is really not a duplicate of Swift Delegate Not Being Called as the solution on that page did not work.
Any help you could provide would be great.
Here's the relevant code snippets:
My weatherGetterController class:
protocol WeatherGetterControllerDelegate {
func getMyWeather(weather: [FiveDayForecast])
}
class WeatherGetterController: UIViewController, CLLocationManagerDelegate {
var weatherGetterDelegate: WeatherGetterControllerDelegate?
And in the WeatherGetterController "getWeather" function call. The line
self.weatherGetterDelegate?.getMyWeather(weather: myForecast)
is not being called.
func getWeather() {
...
getNetWeather { (fetchedInfo) in
if let fetchedInfo2 = fetchedInfo {
//self.updateUI(mainWeather: fetchedInfo2)
//need to call delegate here
let myForecast = self.figureFive(weather: fetchedInfo2)
//return the forecast
print(myForecast)
self.weatherGetterDelegate?.getMyWeather(weather: myForecast)
}
}
Finally the function implementation in NoteTakerViewController:
class NoteTakerViewController: UIViewController, ..., UITextFieldDelegate, WeatherGetterControllerDelegate
func getMyWeather(weather: [FiveDayForecast]) {
print("get my weather")
print(weather)
}
Through debugging I can see that "weatherGetterDelegate" is set to nil and I don't know why.
Thanks
First you need to make WeatherGetterController a property in NoteTakerViewController or a local variable where you call it but I will use the first option.
class NoteTakerViewController: UIViewController, ..., WeatherGetterControllerDelegate {
var weatherGetterController: WeatherGetterController?
//...
func viewDidLoad() {
//....
weatherGetterController = WeatherGetterController()
weatherGetterController?.delegate = self
}
//And then in some other part of your code you do
func someFunc() {
self.weatherGetterController?.getWeather()
I am curious why WeatherGetterController is define to be a viewcontroller, is that really correct?
class WeatherGetterController: UIViewController, CLLocationManagerDelegate {
Personally I would remove that part
class WeatherGetterController: CLLocationManagerDelegate {
Put this in init of WeatherGetterController
public weak var weatherGetterDelegate: WeatherGetterControllerDelegate?
/* if you are not initializing it anywhere else
and if you are initializing it anywhere else then make sure you are
initializing WeatherGetterController there too and then put delegate
of WeatherGetterController to NoteTakerViewController object
else write the below code */
var model = NoteTakerViewController()
public override init() {
self. weatherGetterDelegate = model
}
I have a swift protocol, but it never fires.
I have 1 class which is an instance, and the other is a class where I want to manage an object;
protocol TurnDelegate: class {
func turnIsCompleted()
}
class ClassOne : NSObject {
weak var delegate: TurnDelegate?
override init() {
super.init()
delegate?.turnIsCompleted()
}
}
class ClassTwo: NSObject, TurnDelegate {
static var instance = ClassTwo()
func turnIsCompleted() {
print ("Turn is completed")
}
}
let c2:ClassTwo = ClassTwo.instance
let c1:ClassOne = ClassOne.init()
My issue is that the protocol never fires and does not output "turn is completed"
How can I resolve this?
Edit: How do I set the delegate?
Many thanks
In case you have describe create custom init.
class ClassOne : NSObject {
weak var delegate: TurnDelegate?
init(with delegate: TurnDelegate?) {
self.delegate = delegate
delegate?.turnIsCompleted()
}
}
Than:
let c2:ClassTwo = ClassTwo.instance
let c1:ClassOne = ClassOne.init(with: c2)
Output:
Turn is completed
You forgot to set the delegate.
Usually the delegate is set in an init method. The method in the protocol is called later in another method for example
protocol TurnDelegate: class {
func turnIsCompleted()
}
class ClassOne : NSObject {
weak var delegate: TurnDelegate?
init(delegate: TurnDelegate?) {
self.delegate = delegate
}
func turnSomething()
{
delegate?.turnIsCompleted()
}
}
class ClassTwo: NSObject, TurnDelegate {
static let instance = ClassTwo()
func turnIsCompleted() {
print ("Turn is completed")
}
}
let c2 = ClassTwo.instance
let c1 = ClassOne(delegate: c2)
c1.turnSomething()
However for this purpose especially in conjunction with a singleton I'd prefer a callback closure rather than protocol / delegate. The benefit is less overhead and the callback is directly connected to the calling method.
class ClassOne : NSObject {
func turnSomething()
{
let c2 = ClassTwo.instance
c2.turn {
print ("Turn is completed")
}
}
}
class ClassTwo: NSObject {
static let instance = ClassTwo()
func turn(completion: ()->()) {
// do heavy work
completion()
}
}
let c1 = ClassOne()
c1.turnSomething()
Delegates in all their glory do have their drawbacks too. One of them is that relationships between objects and their delegates have to be established explicitly. In Cocoa there are typically two ways of doing this. One is connecting a delegate IBOutlet in InterfaceBuilder, the other is doing it programmatically. As #OlegGordiichuck points out you could do it in the initializer, but generally in Cocoa delegates tend to be properties. In your case this would boil down to instantiate objects of ClassTwo and ClassOne and then manually set the delegate of c2 as in
c2.delegate = c1
This however defeats your notification mechanism and you would have to have a separate method for notifying the delegate (Which is again typical, as usually your delegate cannot know about is significant other during its construction. Moreover the construction of the originator is usually not something the delegate would have to know about).
In my app I have one screen divided between two ViewControllers - LadderViewController and GameHistoryTableViewController, which lies in a container. I want user to be able to filter the data in the table by tapping on something in the LadderView. I tried to solve this using delegates:
LadderViewController:
delegate = GameHistoryTableViewController()
func imageTapped(imageIndex: Int) {
delegate?.selectedHeroNumber(imageIndex)
}
GameHistoryTableViewController: (conforms to the delegate protocol and implemets a function from it)
func selectedHeroNumber(heroNumber: Int) {
let filteredGames = filterGamesFromHeroNumber(heroNumber)
tableDataSource = filteredGames
self.tableView.reloadData()
}
That doesn't work, though, because the delegate I declare in LadderViewConroller is another instance of GameHistoryTableViewController, not the (to the user) shown one. I don't know how to access the "visible" instance (table) of GameHistoryTableViewController though... So, how should be delegating used here? Or should I use another approach (and if so, what kind)? I basically need to change the table's data source according to on what the user taps, one can say "from outside" (dataSource is a property in my GameHistoryTableViewController class).
Here is an example with delegation like you want to do. It's a better solution than singleton in this case ;)
declare a new protocol call HeroInfo:
protocol HeroInfo: class {
func selectedHeroNumber(heroNumber: Int);
}
LadderViewController:
//create the delegation
weak var delegate:HeroInfo?
func imageTapped(imageIndex: Int) {
//call the delegate method
delegate?.selectedHeroNumber(imageIndex)
}
GameHistoryTableViewController:
// Here get the protocol HeroInfo inheritance
class userTableViewController: UITableViewController, HeroInfo {
override func viewDidLoad() {
super.viewDidLoad()
//Here get your Ladder view in a splitView
if let split = self.splitViewController {
let controllers = split.viewControllers
self.ladderViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? ladderViewController
//register it to delegate
self.ladderViewController?.delegate = self
}
}
...
// Here is your method of your protocol that you must conform to
func selectedHeroNumber(heroNumber: Int) {
let filteredGames = filterGamesFromHeroNumber(heroNumber)
tableDataSource = filteredGames
self.tableView.reloadData()
}
...
}
There are a few ways to achieve this, I have a similar setup for which I use a model class with a singleton to store the relevant data.
For instance you could have the following
class dataModel {
static let sharedInstance = dataModel()
private var _heroNumber = Int()
private init() {}
var heroNumber: Int = {
return _heroNumber
}
func setHero(hero: Int) -> Int {
return _heroNumber
}
}
}
You can then can access this model from each of your controllers using dataModel.sharedInstance.heroNumber etc...
I'm new to using delegates in Swift, and I can't seem to figure out how to communicate with my View Controller from a different class. Specifically, I call the custom class's functions from my App Delegate, and then from within that custom class, I call a function within my View Controller. My basic setup, following this question, is:
AppDelegate.swift:
var customClass = customClass()
func applicationDidFinishLaunching(aNotification: NSNotification) {
customClass.customFunction()
}
CustomClass.swift:
weak var delegate: ViewControllerDelegate?
func customFunction() {
delegate?.delegateMethod(data)
}
ViewController.swift:
protocol ViewControllerDelegate: class {
func customFunction(data: AnyObject)
}
class ViewController: NSViewController, ViewControllerDelegate
func customFunction(data: AnyObject){
println("called")
}
}
However, delegate is always nil. I am assuming this is either because the ViewControllerDelegate protocol never gets initialized or because I never set the delegate of the actual NSViewController? I know I'm missing something obvious/straightfoward, however I have yet to see what that is.
Your question is hard to answers because you have completely misunderstood the point of a protocol.
A protocol is a type which is used to define functionality. A class that conforms to this protocol provides the specified functionality, by implementing the required methods.
You can not initialize a protocol.
So if your CustomClass looks like this:
class CustomClass {
weak var delegate: ViewControllerDelegate?
func customFunction() {
delegate?.delegateMethod(data)
}
}
Why do you expect that delegate has suddenly a value?
Of course you have to set delegate to something first. The delegate must set delegate. If you want a ViewController instance to be the delegate, it must assign itself to delegate.
This for instance will work.
protocol ViewControllerDelegate {
func delegateMethod(data: AnyObject) //I renamed this because in
//CustomClass you are trying to call `delegateMethod` on the delegate
}
class CustomClass {
weak var delegate: ViewControllerDelegate?
func customFunction() {
delegate?.delegateMethod(data)
}
}
class ViewController: NSViewController, ViewControllerDelegate
var customClass = CustomClass()
func viewDidLoad(){
customClass.delegate = self
customClass.customFunction()
}
func delegateMethod(data: AnyObject){
println("called")
}
}
Read more about delegation here.