I have a UITableViewController subclass called LogbookFormTVC that conforms to UIPopoverPresentationControllerDelegate. In this class I have a function that creates and shows a popover:
// --------------------
// LogbookFormTVC.swift
// --------------------
class LogbookFormTVC: UITableViewController, UIAdaptivePresentationControllerDelegate, UIPopoverPresentationControllerDelegate {
#IBAction func tapShowPopover(sender: AnyObject) {
//Tap to show the popover
self.presentViewController(showAircraftPicker(), animated: true, completion: nil)
}
//Build the popover
func showAircraftPicker() -> UIViewController{
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
let pc = aircraftModal.popoverPresentationController
pc?.sourceView = self.view
pc?.delegate = self
return aircraftModal
}
}
I want to move this showAircraftPicker() function and make it available anywhere in my app, so I move it to another file like this:
// --------------------
// SomeWhereElse.swift
// --------------------
//This works
func showAircraftPicker(controller: LogbookFormTVC) -> UIViewController{
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
let pc = aircraftModal.popoverPresentationController
pc?.sourceView = self.view
pc?.delegate = self
return aircraftModal
}
Note how I have to set the type of controller to LogbookFormTVC in order for its protocol conformity to come in with it. But I want this function to work with any class (that conforms to the right protocol, of course).
So doing this doesn't work:
func showAircraftPicker(controller: AnyObject) -> UIViewController{
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
let pc = aircraftModal.popoverPresentationController
pc?.sourceView = self.view
pc?.delegate = self <-- !!! Type AnyObject does not conform to protocol UIPopoverPresentationControllerDelegate !!!
return aircraftModal
}
How can I make this function work with any class and pass on that class's protocol conformity?
You could try to create and extension for UIViewController like this:
extension UIViewController {
func showAircraftPicker(delegate: UIPopoverPresentationControllerDelegate) {
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
let pc = aircraftModal.popoverPresentationController
pc?.sourceView = self.view
pc?.delegate = delegate
return aircraftModal
}
}
Note how I have to set the type of controller to LogbookFormTVC in order for its protocol conformity to come in with it. But I want this function to work with any class (that conforms to the right protocol, of course).
Great. So pass an object of the type "conforms to the right protocol:"
func showAircraftPicker(controller: UIPopoverPresentationControllerDelegate) -> UIViewController{
This is exactly what protocols exist to allow you to do.
If you want to conform to multiple restrictions simultaneously, a generic is handy:
func showAircraftPicker<T: UIViewController
where T:UIPopoverPresentationControllerDelegate>(controller: T) -> UIViewController {
Related
I am attempting to write a func that 1) instantiates a subclass of UIViewController and 2) pushes into the navigation controller of the caller UIViewController.
So far, I have this:
func pushAnyViewController<T>(viewController:T, storyboardName:String) {
// Instantiate the view controller of type T
guard let nextViewController = UIStoryboard(name: storyboardName, bundle: nil).instantiateViewController(withIdentifier: String(describing: T.self)) as? T else {
return
}
viewController.navigationController.pushViewController(nextViewController, animated: true)
}
This produces error
Value of type 'T' has no member 'navigationController'
I am not sure if somehow I should say that T will always be a subclass of UIViewController. If that is the case, it's not clear where I do that. For this, I thought about:
func pushAnyViewController<T>(viewController:T & UIViewController, storyboardName:String)
but that produces errors:
Generic parameter 'T' is not used in function signature
Non-protocol, non-class type 'T' cannot be used within a protocol-constrained type
You need to identify that T is a vc with <T:UIViewController>
func pushAnyViewController<T:UIViewController>(viewController:T, storyboardName:String) {
guard let nextViewController = UIStoryboard(name: storyboardName, bundle: nil).instantiateViewController(withIdentifier: String(describing: T.self)) as? T else { return }
viewController.navigationController?.pushViewController(nextViewController, animated: true)
}
The top answer didn't suit me, I needed a more generic solution. First, I needed the option to pass data, second, I wanted to have a generic function that can push or present VC, and last, I wanted that my generic function can be called from anywhere, not just from the UIViewController, that's why an extension of UIViewController didn't suit me.
I decided to create a struct with simple init, and two public methods so that I can create the copy anywhere and call those methods.
struct Navigator {
// MARK: - DisplayVCType enum
enum DisplayVCType {
case push
case present
}
// MARK: - Properties
private var viewController: UIViewController
static private let mainSBName = "Main"
// MARK: - Init
init(vc: UIViewController) {
self.viewController = vc
}
// MARK: - Public Methods
public func instantiateVC<T>(withDestinationViewControllerType vcType: T.Type,
andStoryboardName sbName: String = mainSBName) -> T? where T: UIViewController {
let storyBoard: UIStoryboard = UIStoryboard(name: sbName, bundle: nil)
let destinationVC = storyBoard.instantiateViewController(withIdentifier: String(describing: vcType.self))
return destinationVC as? T
}
public func goTo(viewController destinationVC: UIViewController,
withDisplayVCType type: DisplayVCType = .present,
andModalPresentationStyle style: UIModalPresentationStyle = .popover) {
switch type {
case .push:
viewController.navigationController?.pushViewController(destinationVC, animated: true)
case .present:
destinationVC.modalPresentationStyle = style
viewController.present(destinationVC, animated: true, completion: nil)
}
}
}
and example call in some VC, with passing string after push:
class SomeVC: UIViewController {
var navigator: Navigator?
override func viewDidLoad() {
super.viewDidLoad()
navigator = Navigator(vc: self)
}
func pushVC() {
guard let vc = navigator?.instantiateVC(withDestinationViewControllerType: VC1.self) else { return }
vc.someString = "SOME STRING TO BE PASSED"
navigator?.goTo(viewController: vc, withDisplayVCType: .push)
}
func presentVC() {
guard let vc = navigator?.instantiateVC(withDestinationViewControllerType: TableViewController.self) else { return }
navigator?.goTo(viewController: vc, withDisplayVCType: .present)
}
}
With Help of some keyword.
enum Storyboard : String {
case Main
}
func viewController(_ viewController: UIViewController.Type) -> some UIViewController {
return UIStoryboard(name: self.rawValue, bundle: nil).instantiateViewController(withIdentifier: String(describing: viewController.self))
}
nil Delegate between two ViewController with two different Bundle using swift 4 (commented in second code)
here is my code :
First ViewController :
class FirstVC : UIViewController, MerchantResultObserver{
var secVC = SecondVC()
override func viewDidLoad() {
secVC.delegate = self
let storyboard = UIStoryboard(name: “SecondVC”, bundle: Bundle(identifier: “SecondBundle”))
let controller = storyboard.instantiateInitialViewController()
self.present(controller!, animated: true, completion: nil)
secVC.initSecondVC(data)
}
func Error(data: String) {
print("-------------Error Returned------------- \(data)")
}
func Response(data: String) {
print("-------------Response Returned------------- \(data)")
}
}
Second ViewController :
public class SecondVC: UIViewController {
public weak var delegate: MerchantResultObserver!
public func initSecondVC(_ data : String){
print(data)
}
#IBAction func sendRequest(_ sender: UIButton) {
delegate?.Response(data: “dataReturnedSuccessfully”) // delegate is nil //
dismiss(animated: true, completion: nil) // returned to FirstVC without returning “dataReturnedSuccessfully” //
}
}
public protocol MerchantResultObserver: class{
func Response(data : String)
func Error(data : String)
}
Any help would be appreciated
var secVC = SecondVC()
and
let storyboard = UIStoryboard(name: “SecondVC”, bundle: Bundle(identifier: “SecondBundle”))
let controller = storyboard.instantiateInitialViewController() as? SecondVC
These both are different instances.
You can assign a delegate to the controller, like
controller.delegate = self
It will call the implemented delegate methods in First View Controller.
Full Code.
let storyboard = UIStoryboard(name: “SecondVC”, bundle: Bundle(identifier: “SecondBundle”))
if let controller = storyboard.instantiateInitialViewController() as? SecondVC {
//Assign Delegate
controller.delegate = self
//It's not init, but an assignment only, as per your code.
controller.initSecondVC(data)
self.present(controller, animated: true, completion: nil)
}
One more thing, Don't present View in ViewDidLoad. You can put a code in some button or in a delay method.
I would like to ask something about type-casting in Swift.
There are 2 classes.
RootViewController
MyViewController
and the class hierarchy is like below:
class RootViewController: UIViewController {
}
class MyViewController: RootViewController {
}
and, I want to simply call instance function to create an instance from xib file.
so I implemented below function in RootViewController.
Objective-C
+ (instancetype)instance {
return [[[self class] alloc] initWithNibName:NSStringFromClass([self class]) bundle:nil];
}
Swift
public class func instance<T:RootViewController>() -> T {
let type = self as UIViewController.Type
let name = NSStringFromClass(type).components(separatedBy: ".").last!
let instance = type.init(nibName: name, bundle: nil)
return instance as! T
}
and, usage is like below.
Objective-C
MyViewController *vc = [MyViewController instance];
Swift
let vc = MyViewController.instance() as! MyViewController
Question:
Do I have to always cast the type of instance using as! MyViewController in Swift?
Or can anybody advise me a better approach in Swift?
Any help would be appreciated!
You can Also use like this way
let vc:MyViewController = MyViewController.instance()
class RootViewController: UIViewController {
public class func instance() -> Self {
func inner<T: RootViewController>(type: T.Type) -> T {
let name = NSStringFromClass(type).components(separatedBy: ".").last!
let type1 = type as UIViewController.Type
let instance = type1.init(nibName: name, bundle: nil)
return instance as! T
}
return inner(type: self)
}
}
I would suggest creating an extension method:
extension UIViewController {
public class func instance() -> Self {
func inner<T: UIViewController>(type: T.Type) -> T {
let name = NSStringFromClass(type).components(separatedBy: ".").last!
return T(nibName: name, bundle: nil)
}
return inner(type: self)
}
}
Okay you can instantiate in these three ways:
Swift inference to Type:
let myVC = RootViewController.instance() //Swift will automatically infer the type
Explicitly telling the Type:
let myVC: RootViewController = RootViewController.instance()
Casting to your Type:
let myVC = RootViewController.instance() as! RootViewController
All these three are valid.
I am opening another ViewController using this:
let mainStoryboard: UIStoryboard = UIStoryboard(name:"Main", bundle:nil)
let homeViewController: UIViewController = mainStoryboard.instantiateViewController(withIdentifier: "IssueViewController")
self.present(homeViewController, animated: true, completion: nil)
Along with this, I need to pass a Person object and a String value to the 2nd ViewController.
struct Person {
var Name: String
var Details: String
}
What changes do I need to do to attach a Person object to my existing code?
EDIT: This is the 2nd ViewController
I am trying to retrieve the values from this view
class IssueViewController: UIViewController {
var person: Person = Person();
override func viewDidLoad() {
super.viewDidLoad()
}
}
//changes in first controller
let mainStoryboard: UIStoryboard = UIStoryboard(name:"Main",bundle:Bundle.main)
let homeViewController: IssueViewController = mainStoryboard.instantiateViewController(withIdentifier: "IssueViewController") as! IssueViewController
homeViewController.person = Person(Name:"ABC",Details:"XYZ")
homeViewController.bindWithData(yourStringObject)
self.present(homeViewController, animated: true, completion: nil)
//changes in second view controller
class IssueViewController: UIViewController {
var person: Person = Person(Name:"",Details:"");
override func viewDidLoad() {
super.viewDidLoad()
print(person.Name)
print(person.Details)
}
func bindWithData(yourStringObject:String){
//your code here.
}
}
I have this function that I use all over my app, and it would be nice to create a global function:
class CustomReportVC: UIViewController, UIAdaptivePresentationControllerDelegate, UIPopoverPresentationControllerDelegate {
func showPicker(pickerValues:[String], field:UITextField) -> AnyPickerVC{
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
let modal = storyboard.instantiateViewControllerWithIdentifier("AnyPickerModal") as! AnyPickerVC
modal.modalPresentationStyle = UIModalPresentationStyle.Popover
let pc = modal.popoverPresentationController
pc?.permittedArrowDirections = .Down
pc?.sourceView = field
pc?.sourceRect = field.bounds
modal.preferredContentSize = CGSizeMake(300,180)
pc?.delegate = self
//Pass in data
modal.data = pickerValues
//Set the value from within the picker controller
modal.passDataToParent = { (value) in
field.text = value
}
return modal
}
//Required for the popover
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return .None
}
}
The issue I'm running into comes with pc?.delegate = self. Since CustomReportVC conforms to UIPopoverPresentationControllerDelegate, this works fine.
But once I attempt to create this as a global function outside a class that conforms to this protocol, I get an error:
func globalShowPicker(pickerValues:[String], field:UITextField, controller:UIViewController) -> AnyPickerVC{
//...
pc?.delegate = controller //<-- ( ! ) Type UIViewController does not conform to UIPopoverPresentationControllerDelegate
}
Whether I make controller a UIViewController or AnyObject, it doesn't conform. Is there a way to pass in the protocol conformity to the global function somehow?
Any idea how I can pull this off? Thanks. :)
Make your global function generic to specify that it only works for certain kinds of UIViewControllers. In this example, T can take the value of any UIViewController type which also conforms to the other protocols listed.
func globalShowPicker< T: UIViewController where
T: UIPopoverPresentationControllerDelegate,
T: UIAdaptivePresentationControllerDelegate >
(pickerValues:[String], field:UITextField, controller: T) -> AnyPickerVC
{
//...
pc?.delegate = controller
return blah
}
It does get kinda long, and I haven't figured out the best way to indent all the constraints. But it works.
Try adding a making a new class that inherits from both of them. Like this.
class PopoverController: UIViewController, UIPopoverPresentationControllerDelegate {
}
Then, switch the function to look like this.
func globalShowPicker(pickerValues:[String], field:UITextField, controller: PopoverController) -> AnyPickerVC{
//...
pc?.delegate = controller
}
You can pass the delegate as a parameter in the function like this:
class CustomReportVC: UIViewController, UIAdaptivePresentationControllerDelegate, UIPopoverPresentationControllerDelegate {
class func showPicker(pickerValues:[String], field:UITextField, delegate: UIPopoverPresentationControllerDelegate) -> UIViewController {
//Set up modal
let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
let modal = storyboard.instantiateViewControllerWithIdentifier("AnyPickerModal") as! UIViewController
modal.modalPresentationStyle = UIModalPresentationStyle.Popover
let pc = modal.popoverPresentationController
pc?.permittedArrowDirections = .Down
pc?.sourceView = field
pc?.sourceRect = field.bounds
modal.preferredContentSize = CGSizeMake(300,180)
pc?.delegate = delegate
//Pass in data
modal.data = pickerValues
//Set the value from within the picker controller
modal.passDataToParent = { (value) in
field.text = value
}
return modal
}
//Required for the popover
func adaptivePresentationStyleForPresentationController(controller: UIPresentationController) -> UIModalPresentationStyle {
return .None
}
}
You have at the end to have an instance of a view controller that does conform to the protocol, but that way you will have the function global just like you want and pass self pointer in the view controller that does conform to the protocol "UIPopoverPresentationControllerDelegate":
CustomReportVC.showPicker(pickerValues:....., delegate: self)
Something like this?
self.presentViewController(pc, animated: true, completion: nil)
Btw, if you're doing Universal you can not present iPad UIActivityViewController like iPhone. You need to present it in a popover as per the design guidelines suggested by Apple.
or as an example
#IBAction func shareButtonClicked(sender: UIButton)
{
let textToShare = "Text"
if let myWebsite = NSURL(string: "http://www.example.com/")
{
let objectsToShare = [textToShare, myWebsite]
let activityVC = UIActivityViewController(activityItems: objectsToShare, applicationActivities: nil)
var nav = UINavigationController(rootViewController: activityVC)
nav.modalPresentationStyle = UIModalPresentationStyle.Popover
var popover = nav.popoverPresentationController as UIPopoverPresentationController!
activityVC.preferredContentSize = CGSizeMake(500,600)
popover.sourceView = self.view
popover.sourceRect = CGRectMake(100,100,0,0)
self.presentViewController(nav, animated: true, completion: nil)
}
}
class MyViewController : UIViewController, UIPopoverPresentationControllerDelegate {
//code here
}