I'm trying to use delegation and property observers together to know when a property changes. I setup the protocol but I'm not sure how to use property observers.
I have a class called GridView that is being added to DetailViewController. GridView has an array of ints called rowValues. I would like to observe rowValues from DetailViewController.
GridView.swift
protocol gridViewDelegate {
func rowValueChanged(value: [Int])
}
class GridView: UIView {
var rowValues = [0,0,0,0,0]
var delegate: gridViewDelegate?
func updateRowValue() {
rowValues[0] = 1
}
}
DetailViewController.swift
class DetailViewController: UIViewController, gridViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
var grid = GridView(frame: view.frame)
grid.delegate = self
view.addSubview(grid)
}
func rowValueChanged(value: [Int]) {
println(value)
}
}
Probably this is the syntax you are looking for:
class GridView: UIView {
var rowValues: [Int] = [0,0,0,0,0] {
didSet {
if let theDelegate = self.delegate {
theDelegate.rowValueChanged(rowValues)
}
}
}
var delegate: gridViewDelegate?
}
Related
I am trying to setup a success/error view on a controller via protocol and extensions.
What I want to achieve is that I want to get into the state where it is enough to implement the protocol on a controller, and from there get access to the successView (no additional boilerplate).
This is what I have so far:
protocol SucessViewProtocol where Self: UIViewController {
func initSuccessView()
var successView: UIView! { get set }
var topConstraint: NSLayoutConstraint! { set get }
func showSuccess()
func hideSucess()
}
extension SucessViewProtocol {
func showSuccess() {
//animate displaying success message
}
func hideSucess() {
//animate hiding success message
}
func initSuccessView() {
successView = UIView()
topConstraint = NSLayoutConstraint()
// init success view and top constraint
}
}
Now when I implement the protocol on the controller it looks like this:
// MARK: SuccessView
extension ConsumingViewController: SucessViewProtocol {
var successView: UIView! {
get {
//getter
}
set {
//setter
}
}
var topConstraint: NSLayoutConstraint! {
get {
//getter
}
set {
//setter
}
}
}
I guess my problem is obvious because I get the successView and topConstraint as properties inside my controller that is implementing the SucessViewProtocol. I am initializing the properties from the protocol inside the extension, so what I need would be just an access to these properties (not declaring them again in my controller). I guess I am missing some "glue" part between the protocol - extension - controller
I want to be able to implement the protocol on a controller, call initSuccessView() and from there it should just be enough to call showSuccess and hideSuccess.
Edit:
This is how I want to use this construct:
class ConsumingViewController: UIViewController {
func viewDidLoad() {
initSuccessView()
loadData()
}
private func loadData() {
//successfullyloaded
showSuccess()
}
}
// MARK: SuccessView
extension ConsumingViewController: SucessViewProtocol {
var successView: UIView! {
get {
//getter
}
set {
//setter
}
} *PROBLEMATIC*
var topConstraint: NSLayoutConstraint! {
get {
//getter
}
set {
//setter
}
} *PROBLEMATIC*
}
As I said, the problem is that the properties successView and topConstraing are being redeclared inside ConsumingViewController (because they are part of the protocol). I would need to actually not be visibile inside the controller, but just being used inside the extension. But then there is the problem with stored properties inside extensions ...
May be you want this?
protocol SucessViewProtocol {
func showSuccess()
func hideSucess()
}
fileprivate struct Key {
static var runtimeKey: Int = 0
}
extension SucessViewProtocol where Self: UIViewController {
var successView: UIView? {
get {
return objc_getAssociatedObject(self, &Key.runtimeKey) as? UIView
}
set {
objc_setAssociatedObject(self, &Key.runtimeKey, newValue, .OBJC_ASSOCIATION_RETAIN)
}
}
func showSuccess() {
successView = UIView()
//animate displaying success message
view.addSubview(successView)
}
func hideSucess() {
//animate hiding success message
successView?.removeFromSuperview()
}
}
add protocol variables inside main scope not extension scope UIViewController like this.
public class ViewController: UIViewController, SucessViewProtocol {
var successView: UIView!
var topConstraint: NSLayoutConstraint!
}
By doing this you do not need to define getter and setter for properties
and inside ViewDidLoaded you can initSuccessView:
public override func viewDidLoad() {
super.viewDidLoad()
self.initSuccessView()
}
and call custom function:
func show() {
self.showSuccess()
}
func hide() {
self.hideSucess()
}
Solution = Optional Porotocols
You just need add properties to the extension as well to make them optional.
protocol SucessViewProtocol where Self: UIViewController {
func initSuccessView()
var successView: UIView! { get set }
var topConstraint: NSLayoutConstraint! { set get }
func showSuccess()
func hideSucess()
}
extension SucessViewProtocol {
// 👇🏼------ these 2 properties added ------👇🏼
var successView: UIView! { get{ nil } set{} }
var topConstraint: NSLayoutConstraint! { get{ nil } set{} }
func showSuccess() {}
func hideSucess() {}
func initSuccessView() {
successView = UIView()
topConstraint = NSLayoutConstraint()
}
}
Then, when you conform SucessViewProtocol on ConsumingViewController you won't require to implement protperties.
// MARK: SuccessView
extension ConsumingViewController: SucessViewProtocol {
// There's NO compiler error here!
}
I needed to delegate an click action for my UIView class to my UIViewController class since swift does not support multiple class inheritance. So i wanted it such that once a button is clicked on my subview, a function in my ViewController class is called. Am using protocol delegate to achieve this but on the click of my button it does not work for me as the function does not get called. Please help me out. Code snippet would be largely appreciated.
ViewController
var categoryItem: CategoryItem! = CategoryItem() //Category Item
private func setupExplore() {
//assign delegate of category item to controller
self.categoryItem.delegate = self
}
//function to be called
extension BrowseViewController: ExploreDelegate {
func categoryClicked(category: ProductCategory) {
print("clicked")
let categoryView = ProductByCategoryView()
categoryView.category = category
categoryView.modalPresentationStyle = .overCurrentContext
self.navigationController?.pushViewController(categoryView, animated: true)
}
}
Explore.swift (subview)
import UIKit
protocol ExploreDelegate:UIViewController {
func categoryClicked(category: ProductCategory)
}
class Explore: UIView {
var delegate: ExploreDelegate?
class CategoryItem: UIView {
var delegate: ExploreDelegate?
var category: ProductCategory? {
didSet {
self.configure()
}
}
var tapped: ((_ category: ProductCategory?) -> Void)?
func configure() {
self.layer.cornerRadius = 6
self.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.categoryTapped)))
self.layoutIfNeeded()
}
#objc func categoryTapped(_ sender: UIGestureRecognizer) {
delegate?.categoryClicked(category: ProductCategory.everything)
self.tapped?(self.category)
}
}
I want to trigger Navigation controller to some other screen when i press the button in UIView class. How can i do this?
//Code for UIView Class in Which Button Iboutlet is created
import UIKit
protocol ButtonDelegate: class {
func buttonTapped()
}
class SlidesVC: UIView {
var delegate: ButtonDelegate?
#IBAction func onClickFinish(_ sender: UIButton) {
delegate?.buttonTapped()
}
#IBOutlet weak var imgProfile: UIImageView!
}
//ViewController Class code in Which Button Protocol will be entertained
class SwipingMenuVC: BaseVC, UIScrollViewDelegate {
var slidesVC = SlidesVC()
override func viewDidLoad() {
super.viewDidLoad()
slidesVC = SlidesVC()
// add as subview, setup constraints etc
slidesVC.delegate = self
}
extension BaseVC: ButtonDelegate {
func buttonTapped() {
self.navigationController?.pushViewController(SettingsVC.settingsVC(),
animated: true)
}
}
A more easy way is to use typealias. You have to write code in 2 places. 1. your viewClass and 2. in your View Controller.
in your SlidesView class add a typealias and define param type if you need otherwise leave it empty.
class SlidesView: UIView {
typealias OnTapInviteContact = () -> Void
var onTapinviteContact: OnTapInviteContact?
#IBAction func buttonWasTapped(_ sender: UIButton) {
if self.onTapinviteContact != nil {
self.onTapinviteContact()
}
}
}
class SwipingMenuVC: BaseVC, UIScrollViewDelegate {
override func viewDidLoad() {
super.viewDidLoad()
let slidesView = SlidesView()
slidesView.onTapinviteContact = { () in
// do whatever you want to do on button tap
}
}
You can use the delegate pattern to tell the containing ViewController that the button was pressed and let it handle whatever is needed to do next, The view doesn't really need to know what happens.
A basic example:
protocol ButtonDelegate: class {
func buttonTapped()
}
class SomeView: UIView {
var delegate: ButtonDelegate?
#IBAction func buttonWasTapped(_ sender: UIButton) {
delegate?.buttonTapped()
}
}
class ViewController: UIViewController {
var someView: SomeView
override func viewDidLoad() {
someView = SomeView()
// add as subview, setup constraints etc
someView.delegate = self
}
}
extension ViewController: ButtonDelegate {
func buttonTapped() {
self.showSomeOtherViewController()
// or
let vc = NewViewController()
present(vc, animated: true)
}
}
I am using xlpagertabstrip and I have a parent view controller which has two children (child1, child2).
In my parent view controller, I show a UIActivityViewIndicator but I want to know how to hide that indicator in my child1.
This is my code:
ParentViewController:
override func viewDidLoad() {
showActivityIndicator()
super.viewDidLoad()
}
func showActivityIndicator() {
//code related to titleview
navigationItem.titleView = titleView
}
func hideActivityIndicator() {
navigationItem.titleView = nil
}
Child1ViewController:
override func viewDidLoad() {
super.viewDidLoad()
call_api()
}
func call_api(){
//code related to api
//if api is ok, I call hideActivityIndicator()
let pctrl = ParentViewController()
pctrl.hideActivityIndicator()
}
But that code does not work. How can I solve that?
Just pass hideActivityIndicator() from the parent to the child and call it when necessary. So whenever you create your child controller do this:
// Parent Controller
childVC.someMethodFromParent = hideActivityIndicator
And in your ChildController do this:
// Child Controller
internal var someProperty: (() -> Void)!
override func viewDidLoad() {
super.viewDidLoad()
call_api()
}
func call_api(){
//code related to api
//if api is ok, I call hideActivityIndicator()
someMethodFromParent()
}
This should work
How about having a ChildViewControllerDelegate? Something like:
class ParentViewController {
func someFunc(){
...
childVC.delegate = self
...
}
}
extension ParentViewController: ChildViewControllerDelegate {
func childViewControllerDidFinishApiCall() {
hideActivityIndicator()
}
}
protocol ChildViewControllerDelegate: class {
func childViewControllerDidFinishApiCall()
}
class ChildViewController {
weak var delegate: ChildViewControllerDelegate?
func call_api(){
//code related to api
let pctrl = ParentViewController()
delegate?.childViewControllerDidFinishApiCall()
}
}
I'm new to swift and am making an graphing app with two views where one has a text field to enter data and the other has a view to display the data. I've got the data as two arrays of doubles in my ViewController class, but I can't move the data to the class of UIView where I want to draw to the view it because it does not inherit the arrays. I've tried accessor methods but that hasn't changed anything.
Here is the class that contains xValues and yValues
class ViewController: UIViewController {
#IBOutlet var DataEntry: UITextView!
var xValues = Array<Double>()
var yValues = Array<Double>()
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
//the xValues and yValues arrays are filled when the view changes on the press of a button
}
public func getXCord() -> Array<Double>{
return xValues
}
public func getYCord() -> Array<Double>{
return yValues
}
}
Here is the class I want them delivered to. I'm getting an error when initializing xCords and yCords to ViewController.getXCord() and ViewController.getYCord() respectively.
class GraphView: UIView{
var points: [Points] = []
var xCords: Array<Double> = ViewController.getXCord()
var yCords: Array<Double> = ViewController.getYCord()
var position = CGPoint(x: 0,y: 0)
}
You are doing this the complete opposite way.
In the MVC pattern, the view, your GraphView class, should never directly talk to the controller. Instead, the view should use a delegate and/or a datasource to communicate with the controller.
Your view should have a GraphViewDatasource:
protocol GraphViewDatasource : class {
func xValues(inGraph: GraphView) -> [Double]
func yValues(inGraph: GraphView) -> [Double]
}
// in GraphView
weak var datasource: GraphViewDatasource?
func reloadData() {
guard let datasource = self.datasource else { return }
xValues = datasource.xValues(inGraph: self)
yValues = datasource.yValues(inGraph: self)
// redraw the graph...
}
Your controller should implement GraphViewDatasource:
class ViewController: UIViewController, GraphViewDatasource {
func xValues(inGraph: GraphView) -> [Double] { return self.xValues }
func yValues(inGraph: GraphView) -> [Double] { return self.yValues }
}
and set self as the data source of the graph view:
let graph = GraphView(frame ...)
self.view.addSubView(graph)
graph.datasource = self
graph.reloadData()
You need to pass xCoords and yCoords to GraphView from ViewController.
First, initialize xCoords and yCoords with empty array:
class GraphView: UIView{
var points: [Points] = []
var xCords: Array<Double> = []
var yCords: Array<Double> = []
var position = CGPoint(x: 0,y: 0)
}
Than pass it from ViewController:
class ViewContoller: UIViewController {
#IBOutlet var graphView: GraphView!
override func viewDidLoad() {
super.viewDidLoad()
graphView.xCoords = self.xCoords
graphView.yCoords = self.yCoords
}
}