I am trying to setup a master details navigation.
I use storyboard, master is a dynamic table and details is a static table.
I have a nameLabel setup as an outlet in the controller but when i try to access it in viewDidLoad, its still set to nil.
Instead of using prepareForSegue, I have used didSelectRowAtIndexPath which pushes the detail view like this: (because i'm using the TableViewBindingHelper, see https://github.com/ColinEberhardt/ReactiveTwitterSearch/tree/master/ReactiveTwitterSearch/Util)
func showLessonView(lessonVM: LessonViewModel) {
let lessonViewController = LessonViewController(WithViewModel: lessonVM)
self.navigationController?.pushViewController(lessonViewController, animated: true)
}
LessonViewController:
import Foundation
import ReactiveCocoa
class LessonViewController: UITableViewController {
#IBOutlet var lessonNameLabel: UILabel!
private var viewModel: LessonViewModel
init(WithViewModel viewModel: LessonViewModel){
self.viewModel = viewModel
super.init(nibName: nil, bundle: nil)
}
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func viewDidLoad() {
super.viewDidLoad()
bindData()
}
func bindData() {
// null here!
if (lessonNameLabel != nil) {
lessonNameLabel.rac_text <~ viewModel.name
}
}
}
How can I fix this?
Other sample code i have seen performs the navigation in segue which ends up calling the init(coder aDecoder: NSCoder) constructor and all the outlets are already initialized.
Because you initialise the view controller with the WithViewModel initialiser, it knows nothing about the storyboard and so the outlets are not hooked up. To get the outlets hooked up as specified in the storyboard, you need either to use a segue, or to use the storyboard's instantiateViewControllerWithIdentifier(identifier:) method to create the view controller. Either way, you can't (easily) pass the ViewModel as an argument for the initialisation, so you will need to expose the viewModel var (remove private) and set it separately in your showLessonView method. To use instantiateViewControllerWithIdentifier(identifier:), give your Lesson View Controller an identifier (say "LessonViewController") in the storyboard. Then amend your showLessonView as follows:
func showLessonView(lessonVM: LessonViewModel) {
let lessonViewController = self.storyboard!.instantiateViewControllerWithIdentifier(identifier:"LessonViewController") as! LessonViewController
lessonViewController.viewModel = lessonVM
self.navigationController?.pushViewController(lessonViewController, animated: true)
}
When a view controller is instantiated from a storyboard, the init(coder:) initialiser is used, so either remove the override of that method, or amend it to call the super implementation:
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
Related
I request apologies in advance in the case this question is very elemental or the answer is obvious.
I have a custom xib, that works very well when used with the storyboard interface builder. The custom xib is implemented like the classical samples you can find across the internet:
I have a CustomView.swift class
a CustomView.xib file.
The FileOwner of the CustomView.xib file is set to the CustomView.class. Then this xib file has a couple of outlets for the views used in the xib. Something like the following:
#IBDesignable
class CustomView: UIView {
#IBOutlet weak var view1: UIView!
#IBOutlet weak var view2: UIView!
required init?(coder aDecoder: NSCoder) {
//When loaded from storyboard.
super.init(coder: aDecoder)
commonInit()
}
override init(frame: CGRect) {
//When loaded from code
super.init(frame: frame)
commonInit()
}
func commonInit() {
if let view = Bundle.main.loadNibNamed(self.nibName, owner: self, options: nil)?.first as? UIView {
view.frame = self.bounds
self.addSubview(view)
view.autoresizingMask = [.flexibleHeight, .flexibleWidth]
}
}
func renderViews()
//A lot of stuff is done here.
}
}
As said, this works very well when using the Storyboard designer to insert the custom xib in the layout of an UIController. But I need to use the same xib on another place, and I need to instantiate and insert it programmatically in a container view multiple times.
I tried different approaches to instantiate the xib and add it as a subview of another view, for example:
class AnotherView: UIView
(...)
func instantiateXib(){
let view = CustomView()
self.addSubView(view)
}
}
or
class AnotherView: UIView
(...)
func instantiateXib(){
let nib = UINib(nibName: "CustomView", bundle: nil).instantiate(withOwner: nil, options: nil)
let view = nib.first as! CustomView
self.addSubView(view)
}
}
or many other ways that I found across the internet, but all of them end with an infinite loop, because the method init?(coder aDecoder: NSCoder) of the xib, calls the commonInit method that instantiates again an instance of the xib, and so on.
I suspect the solution is obvious, but I'm struggling to find it.
May you point me in the right direction? Thank you in advance!
I want to create a reusable button all over my app and was planning to design it with it's own .xib file. The issue is that I can't connect an IBAction to the custom button in the controllers where it's used.
I created a new .xib file called SampleButton.xib and added a button. This is what the hierarchy and the view looks like:
I then created a new swift file called SampleButton.swift with a class called SampleButton that's a subclass of UIButton and assigned it as the File's Owner in my SampleButton.xib file.
The contents of SampleButton.swift are as follows:
import Foundation
import UIKit
#IBDesignable
class SampleButton: UIButton {
override init(frame: CGRect) {
super.init(frame: frame)
setup()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
setup()
}
func setup() {
guard let view = loadViewFromNib() as? UIButton else {
return
}
view.frame = bounds
view.autoresizingMask = [UIView.AutoresizingMask.flexibleWidth,
UIView.AutoresizingMask.flexibleHeight]
addSubview(view)
view.layer.borderWidth = 2
view.layer.borderColor = UIColor.white.cgColor
}
func loadViewFromNib() -> UIView? {
let bundle = Bundle(for: type(of: self))
let nib = UINib(nibName: String(describing: type(of: self)), bundle: bundle)
return nib.instantiate(withOwner: self, options: nil).first as? UIButton
}
#IBAction func pressed(_ sender: Any) {
print("Called in here")
}
}
I can then create a new button in my storyboard and set it to custom and the class to SampleButton. However now if I ctrl + drag from my button to my corresponding View Controller to create an IBAction for the button, it's not called. The one in the SampleButton.swift file is. Even if I delete the IBAction in the SampleButton file it's still not called.
Any help here? I want to be able to design the buttons separately and then have IBactions for them in the controllers where they're used.
I encountered this same issue with some of my custom xib views and my initial thought was that I could set up my xib to be IBDesignable and then connect outlets from the storyboard rendering of my button in the view controller.
That didn't work.
So I setup a bit of a workaround using delegate callbacks from my custom views. I created IBOutlets for the view to the view controllers using them, then in viewDidLoad I'd set the delegate and handle the button tap in the view controller
import UIKit
// defines a callback protocol for the SampleButtonView
protocol SampleButtonViewDelegate: class {
func sampleButtonTapped(_ button: SampleButton)
}
#IBDesignable
class SampleButton: UIView, NibLoadable {
// create IBOutlet to button if you want to register a target/action directly
#IBOutlet var button: UIButton!
// set delegate if you want to handle button taps via delegate
weak var delegate: SampleButtonViewDelegate?
// initializers to make it so this class renders in view controllers
// when using IBDesignable
convenience init() {
self.init(frame: .zero)
}
override init(frame: CGRect) {
super.init(frame: frame)
loadFromNib(owner: self)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
loadFromNib(owner: self)
}
#IBAction func buttonTapped(_ sender: Any) {
delegate?.sampleButtonTapped(_ button: self)
}
}
// here's a sample ViewController using this view and the delegate callback method
class ViewController: UIViewController {
#IBOutlet var sampleButtonView: SampleButton!
override func viewDidLoad() {
super.viewDidLoad()
sampleButtonView.delegate = self
}
}
extension ViewController: SampleButtonViewDelegate {
func sampleButtonTapped(_ button: SampleButton) {
// TODO: run logic for button tap here
}
}
For completeness I'll also add this NibLoadable protocol definition here.
// I used this for the #IBDesignable functionality to work and actually render
// my xib layouts in the storyboard view controller layouts using this class
import UIKit
/// Defines an interface for UIViews defined in .xib files.
public protocol NibLoadable {
// the name of the associated nib file
static var nibName: String { get }
// loads the view from the nib
func loadFromNib(owner: Any?)
}
public extension NibLoadable where Self: UIView {
/// Specifies the name of the associated .xib file.
/// Defaults to the name of the class implementing this protocol.
/// Provide an override in your custom class if your .xib file has a different name than it's associated class.
static var nibName: String {
return String(describing: Self.self)
}
/// Provides an instance of the UINib for the conforming class.
/// Uses the bundle for the conforming class and generates the UINib using the name of the .xib file specified in the nibName property.
static var nib: UINib {
let bundle = Bundle(for: Self.self)
return UINib(nibName: Self.nibName, bundle: bundle)
}
/// Tries to instantiate the UIView class from the .xib file associated with the UIView subclass conforming to this protocol using the owner specified in the function call.
/// The xib views frame is set to the size of the parent classes view and constraints are set to make the xib view the same size as the parent view. The loaded xib view is then added as a subview.
/// This should be called from the UIView's initializers "init(frame: CGRect)" for instantiation in code, and "init?(coder aDecoder: NSCoder)" for use in storyboards.
///
/// - Parameter owner: The file owner. Is usually an instance of the class associated with the .xib.
func loadFromNib(owner: Any? = nil) {
guard let view = Self.nib.instantiate(withOwner: owner, options: nil).first as? UIView else {
fatalError("Error loading \(Self.nibName) from nib")
}
view.frame = self.bounds
view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
addSubview(view)
}
}
You could also simply register the functions you defined in your view controller as the target/action functions for the button in the custom view.
override func viewDidLoad() {
super.viewDidLoad()
mySampleButtonView.button.addTarget(self, action: #selector(buttonTapped(_:)), for: .touchUpInside)
}
#objc func buttonTapped(_ sender: UIButton) {
// handle button tap action in view controller here...
}
create iboutlet of button in nib class.
add you nib view in your viewcontroller where its needed.
add target for the button outlet.
try following code:
override func viewDidLoad() {
super.viewDidLoad()
let myButton = Bundle.main.loadNibNamed("myButtonxibName", owner: self, options: nil)?[0] as? myButtonxibClassName
myButton.button.addTarget(self, action: #selector(buttonTapped(_:)), for: .touchUpInside)
self.view.addsubview(myButton)
}
#objc func buttonTapped() {}
You don't need a Xib for what you're trying to do. Remove the loadViewFromNib() and the pressed(_ sender: Any) functions from your class above. Change your setup() method to customize your button. I see that you want to add a border to it. Do something like this:
func setup() {
self.layer.borderWidth = 2
self.layer.borderColor = UIColor.white.cgColor
// * Any other UI customization you want to do can be done here * //
}
In your storyboard, drag and drop a regular UIButton wherever you want to use it, set the class in the attributes inspector to SampleButton, connect your IBOutlet and IBActions as necessary, and it should be good to go.
I don't think it's possible to do this. Simpler way is to just set the target and action in view controllers. Something like:
class VC: UIViewController {
func viewDidLoad() {
sampleButton.addTarget(self, action: #selector(didClickOnSampleButton))
}
}
I work with Nibs. I have two screens that will use the "same" UIView component with the same behavior. It's not the same component because in each screen i placed a UIView and made the same configuration, as show on the image.
To solve this and prevent replicate the same code in other classes i wrote one class, that is a UIView subclass, with all the functions that i need.
After that i made my custom class as superclass of these UIView components to inherit the IBOutlets and all the functions.
My custom class is not defined in a Nib, is only a .swift class.
I made all the necessary connections but at run time the IBOutlets is Nil.
The code of my custom class:
class FeelingGuideView: UIView {
#IBOutlet weak var firstScreen: UILabel!
#IBOutlet weak var secondScreen: UILabel!
#IBOutlet weak var thirdScreen: UILabel!
#IBOutlet weak var fourthScreen: UILabel!
private var labelsToManage: [UILabel] = []
private var willShow: Int!
private var didShow: Int!
override init(frame: CGRect) {
super.init(frame: frame)
self.initLabelManagement()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.initLabelManagement()
}
private func initLabelManagement() {
self.initLabelVector()
self.willShow = 0
self.didShow = 0
self.setupLabelToShow(label: labelsToManage[0])
self.setupLabels()
}
private func initLabelVector() {
self.labelsToManage.append(self.firstScreen)
self.labelsToManage.append(self.secondScreen)
self.labelsToManage.append(self.thirdScreen)
self.labelsToManage.append(self.fourthScreen)
}
private func setupLabels() {
for label in labelsToManage {
label.layer.borderWidth = 2.0
label.layer.borderColor = UIColor(hex: "1A8BFB").cgColor
}
}
func willShowFeelCell(at index: Int) {
self.willShow = index
if willShow > didShow {
self.setupLabelToShow(label: labelsToManage[willShow])
}
else if willShow < didShow {
for i in didShow ... willShow + 1 {
let label = labelsToManage[i]
self.setupLabelToHide(label: label)
}
}
}
private func setupLabelToShow(label: UILabel) {
label.textColor = UIColor.white
label.backgroundColor = UIColor(hex: "1A8BFB")
}
private func setupLabelToHide(label: UILabel) {
label.textColor = UIColor(hex: "1A8BFB")
label.backgroundColor = UIColor.white
}
}
I found this question similar to mine: Custom UIView from nib inside another UIViewController's nib - IBOutlets are nil
But my UIView is not in a nib.
EDIT:
I overrided the awakeFromNib but it neither enter the method.
More explanation:
My custom class is only superClass of this component:
Which i replicate on two screens.
One screen is a UITableViewCell and the another a UIViewController.
It's all about to manage the behavior of the labels depending on the screen that is showing at the moment on the UICollectionView
When the initLabelVector() function is called at the required init?(coder aDecoder:) it arrises a unwrap error:
The error when try to open the View:
Cannot show the error with the UITableViewCell because it is called at the beginning of the app and don't appear nothing. To show the error with the screen i needed to remove the call of the UITableViewCell.
The UITableViewCell is registered first with the tableView.register(nib:) and after using the tableView.dequeueReusebleCell.
The UIViewController is called from a menu class that way:
startNavigation = UINavigationController(rootViewController: FellingScreenViewController())
appDelegate.centerContainer?.setCenterView(startNavigation, withCloseAnimation: true, completion: nil)
The problem is this code:
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.initLabelManagement()
}
The trouble is that init(coder:) is too soon to speak of the view's outlets, which is what initLabelManagement does; the outlets are not hooked up yet. Put this instead:
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func awakeFromNib() {
super.awakeFromNib()
self.initLabelManagement()
}
How I arrived at this answer:
As a test, I tried this:
class MyView : UIView {
#IBOutlet var mySubview : UIView!
required init?(coder aDecoder: NSCoder) {
super.init(coder:aDecoder)
print(#function, self.mySubview)
}
override func awakeFromNib() {
super.awakeFromNib()
print(#function, self.mySubview)
}
}
Here's the output:
init(coder:) nil
awakeFromNib() <UIView: 0x7fc17ef05b70 ... >
What this proves:
init(coder:) is too soon; the outlet is not hooked up yet
awakeFromNib is not too soon; the outlet is hooked up
awakeFromNib is called, despite your claim to the contrary
When the init() from my custom class is called the IBOutlets are not hooked up yet.
So, I created a reference on the parent view and called the iniLabelManagement() from the viewDidLoad() method and everything worked.
Thank you matt, for the help and patience!
I have a view controller as follows:
class TutorialPageViewController: UIViewController, UIPageViewControllerDelegate
{
#IBOutlet weak var pageControl: UIPageControl!
var tutorialCategory = TutorialCategory.enableShareContact
override func viewDidLoad()
{
super.viewDidLoad()
self.pageViewController.dataSource = self
self.pageViewController.delegate = self
pageControl.numberOfPages = 5
...
This runs without problem, however after adding an initializer the pageControl outlet is now nil in viewDidLoad resulting in an exception. This is the initializers added:
init(tutorialCategory: TutorialCategory)
{
super.init(nibName: nil, bundle: nil)
self.tutorialCategory = tutorialCategory
}
convenience required init(coder aDecoder: NSCoder)
{
self.init(tutorialCategory: TutorialCategory.enableShareContact)
}
Why is adding the initializer having this effect of making the IBOutlet now become nil and how do I solve it?
(I tried adding a call to the VC's view within viewDidLoad to attempt to force load the outlet but it had no effect)
Because the outlet is setup by super.init(coder aDecoder: NSCoder), which you are no longer calling.
You probably want:
required init(coder aDecoder: NSCoder) {
self.tutorialCategory = .enableShareContact
super.init(coder: aDecoder)
}
Don't override it as a convenience init.
Apologies if this has been asked before, I've searched around a lot and many answers are from earlier Swift betas when things were different. I can't seem to find a definitive answer.
I want to subclass UIViewController and have a custom initializer to allow me to set it up in code easily. I'm having trouble doing this in Swift.
I want an init() function that I can use to pass a specific NSURL I'll then use with the view controller. In my mind it looks something like init(withImageURL: NSURL). If I add that function it then asks me to add the init(coder: NSCoder) function.
I believe this is because it's marked in the superclass with the required keyword? So I have to do it in the subclass? I add it:
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
Now what? Is my special initializer considered a convenience one? A designated one? Do I call a super initializer? An initializer from the same class?
How do I add my special initializer onto a UIViewController subclass?
class ViewController: UIViewController {
var imageURL: NSURL?
// this is a convenient way to create this view controller without a imageURL
convenience init() {
self.init(imageURL: nil)
}
init(imageURL: NSURL?) {
self.imageURL = imageURL
super.init(nibName: nil, bundle: nil)
}
// if this view controller is loaded from a storyboard, imageURL will be nil
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
For those who write UI in code
class Your_ViewController : UIViewController {
let your_property : String
init(your_property: String) {
self.your_property = your_property
super.init(nibName: nil, bundle: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) is not supported")
}
}
This is very similar to the other answers, but with some explanation. The accepted answer is misleading because its property is optional and doesn't expose the fact that your init?(coder: NSCoder) MUST initialize each and every property and the only solution to that is having a fatalError(). Ultimately you could get away by making your properties optionals, but that doesn't truly answer the OP’s question.
// Think more of a OnlyNibOrProgrammatic_NOTStoryboardViewController
class ViewController: UIViewController {
let name: String
override func viewDidLoad() {
super.viewDidLoad()
}
// I don't have a nib. It's all through my code.
init(name: String) {
self.name = name
super.init(nibName: nil, bundle: nil)
}
// I have a nib. I'd like to use my nib and also initialze the `name` property
init(name: String, nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle? ) {
self.name = name
super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}
// when you do storyboard.instantiateViewController(withIdentifier: "ViewController")
// The SYSTEM will never call this!
// it wants to call the required initializer!
init?(name: String, coder aDecoder: NSCoder) {
self.name = "name"
super.init(coder: aDecoder)
}
// when you do storyboard.instantiateViewController(withIdentifier: "ViewController")
// The SYSTEM WILL call this!
// because this is its required initializer!
// but what are you going to do for your `name` property?!
// are you just going to do `self.name = "default Name" just to make it compile?!
// Since you can't do anything then it's just best to leave it as `fatalError()`
required init?(coder aDecoder: NSCoder) {
fatalError("I WILL NEVER instantiate through storyboard! It's impossible to initialize super.init?(coder aDecoder: NSCoder) with any other parameter")
}
}
You basically have to ABANDON loading it from storyboard. Why?
Because when you call a viewController storyboard.instantiateViewController(withIdentifier: "viewController") then UIKit will do its thing and call
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
You can never redirect that call to another init method.
Docs on instantiateViewController(withIdentifier:):
Use this method to create a view controller object to present
programmatically. Each time you call this method, it creates a new
instance of the view controller using the init(coder:) method.
Yet for programmatically created viewController or nib created viewControllers you can redirect that call as shown above.
Convenience initializers are secondary, supporting initializers for a
class. You can define a convenience initializer to call a designated
initializer from the same class as the convenience initializer with
some of the designated initializer’s parameters set to default values.
You can also define a convenience initializer to create an instance of
that class for a specific use case or input value type.
They are documented here.
If you need a custom init for a popover for example you can use the following approach:
Create a custom init that uses the super init with nibName and bundle and after that access the view property to force the load of the view hierarchy.
Then in the viewDidLoad function you can configure the views with the parameters passed in the initialization.
import UIKit
struct Player {
let name: String
let age: Int
}
class VC: UIViewController {
#IBOutlet weak var playerName: UILabel!
let player: Player
init(player: Player) {
self.player = player
super.init(nibName: "VC", bundle: Bundle.main)
if let view = view, view.isHidden {}
}
override func viewDidLoad() {
super.viewDidLoad()
configure()
}
func configure() {
playerName.text = player.name + "\(player.age)"
}
}
func showPlayerVC() {
let foo = Player(name: "bar", age: 666)
let vc = VC(player: foo)
present(vc, animated: true, completion: nil)
}