I see this topic is discussed elsewhere but I don't see an answer to my questions.
I subclassed UIView to create a custom view. Currently I'm using interface builder to create a UIView and then setting the custom class option to my subclass.
First question. When I do that, how to I reference that instance from my code? I have a public function I would like to call that updates my view but I don't know how to call it from my view controller
Second question. I created an instance of the class from within my view controller just playing around and I noticed the public function I created isn't available with that instance. Can I create public functions when I inherit from UIView?
It is easy to do:
1)subclass UIView to create CustomView, add your public function,in your project:
import UIKit
class CunstomView: UIView {
/*
// Only override draw() if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func draw(_ rect: CGRect) {
// Drawing code
}
*/
public func printHello() {
print("hello")
}
}
2)In your storyboard, drag a UIView into your vc, and set the class to CunstomView, you can see that in my red frame:
3)click the Show the Assistant Editor, and ctrl-drag the view to the vc, set the name custom:
4)then in your vc's viewDidload function, you call the public function:
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var custom: CunstomView!
override func viewDidLoad() {
super.viewDidLoad()
custom.printHello()
}
}
5)the result:
First question. When I do that, how to I reference that instance from
my code? I have a public function I would like to call that updates my
view but I don't know how to call it from my view controller
A: A view cannot exist by itself in app. You need viewcontroller to handle the custom view. Then in that VC, you can refer the view as IBOutlet.
Second question. I created an instance of the class from within my
view controller just playing around and I noticed the public function
I created isn't available with that instance. Can I create public
functions when I inherit from UIView?
A: You can create public function of custom view, just declare them in the header file. Then import the header in your VC. Then u can access it.
You can try to update your view from IB with the mothod below.
Objective-C:
-(void)awakeFromNib {
[super awakeFromNib];
//do something
}
Swift
override func awakeFromNib() {
super.awakeFromNib()
}
Second question
Do you mean the custom view don't answer the function you create within the view controller?
Related
I have two main screens in my app, currently both just subclasses of UIViewController. These two view controllers are very similar - they both implement my custom subclass of UIView called HeaderView that is responsible for displaying information and taking user input. As it stands, this code is repetitive because the HeaderView setup is the same for both view controllers - the only difference is what happens when the user confirms the text entry in HeaderView.
To cut down on repetitive code, I am creating a class called InputViewController (a subclass of UIViewController) that houses the aspects of the two view controllers that are identical. Eventually, I want the two view controllers to subclass InputViewController instead of UIViewController.
class InputViewController: UIViewController, InputProtocol {
private let headerView = HeaderView()
override func viewDidLoad() {
super.viewDidLoad()
// layout, etc.
setupCallbacks()
}
internal func setupCallbacks() {
headerView.onUpdate = { (text: String) in
// called when user confirms text entry in headerView
self.onHeaderUpdate()
}
}
internal func onHeaderUpdate() {} // Blank function
}
setupCallbacks() and onHeaderUpdate() are methods defined in the protocol that the InputViewController conforms to. The HeaderView implements a callback closure that is handled in setupCallbacks() by headerView.onUpdate...
The protocol that InputViewController conforms to:
protocol InputProtocol {
func setupCallbacks()
func onHeaderUpdate()
}
To illustrate this, I drew up a diagram;
Since I want the subclasses of InputViewController to override the onHeaderUpdate() method, is it conventional to leave the definition of onHeaderUpdate() in InputViewController blank or is there another solution to this?
is it conventional to leave the definition of onHeaderUpdate() in InputViewController blank
Yes, that is called an abstract method. It is common to give it code that crashes deliberately, as a way of saying, “I exist only to be overridden in a subclass.”
(I should go further and say that what you are creating, a base view controller that carries out initial configurations that all subclasses must implement, is also normal.)
I have a custom view. I named AnimatingView. I have customized the view in the AnimatingView.swift. In the ViewController, I am initiating the view with
let customAnimatingView = AnimatingView(overView: self.view)
and then I add the subView with -
self.view.addSubview(customAnimatingView)
However, I don't want the user add it as a subView like above, rather. I want to call a func from AnimatingView and the custom view should add it the controller like -
customAnimatingView.preset()
Can anyone give me some hint on how can I achieve such behavior.
Inside the custom view do
// add a property that refers to the the vc container of the view
// init it when you create an instance of the view
weak var parentController:UIViewController?
func present() {
parentController?.view.addSubview(self)
}
OR if you need to send the main view instead
var parentView:UIView?
func present() {
parentView?.addSubview(self)
}
I am developing an app with 10 view controllers, including 2 webview controllers. Every view controller contains a 'send feedback' button on top right with exactly same style and functionality.
Right now, I am writing exact same code in each view controller for the buttons.
I was wondering if there is a way to write the method only at one place and use it for all the buttons, since the function is same.
I am using swift 3.
Create new subclass of view controller:
class SendFeedbackViewController: UIViewController {
#IBOutlet weak var sendFeedbackButton: UIButton!
#IBAction func sendFeedback() {
/* do whatever you need */
}
}
Then subclass all your view controllers from this new view controller:
class YourViewController: SendFeedbackViewController {
/* your entire logic */
}
In storyboard set class type:
Now you can connect your send feedback button outlet and action:
Use extension of UIViewController.
extension UIViewController {
func sendFeedBack() {
//write your code here
}
}
And call from any ViewController.
I'm, relatively, a beginner, so this may be an entirely common practice—or an entirely impossible one—but I've been wondering if it's possible to modify a view controller added in a storyboard so that instead of (or in addition to?) being an instance of UIViewConroller, it's also an instance of (blahblah)ViewController, e.g. ABUnknownPersonViewController.
That way, instead of doing something like this:
class ViewController : UIViewController {
override func viewDidLoad() {
let test = ABUnknownPersonViewController()
...
self.presentViewController(test, animated: false, completion: nil)
}
}
This could be done:
class ViewController : ABUnknownPersonViewController {
override func viewDidLoad() {
//ViewController already is an ABUnknownPersonViewController, so you can treat it as one
//example below (displayedPerson is a property of ABUnkownPersonViewControllers)
self.displayedPerson...
}
}
EDIT: ABUnknownPersonViewController is a class supplied by Apple, which does not support subclassing (here). With that said, and the understanding that I would obviously like as simple a solution as possible (avoidance of protocols and whatnot), what are my options?
I tried class FourthViewController: UIViewController, ABUnknownPersonViewController, ABUnknownPersonViewController, ABUnknownPersonViewControllerDelegate only to get an error about multiple inheritance.
It sounds like what you actually want to do is to subclass UIViewController, and in your storyboard, set the custom class to your subclass. When the view controller is loaded from the storyboard, it will be an instance of your subclass.
So your subclass would look like this:
class ABUnknownPersonViewController : UIViewController {
override func viewDidLoad() {
self.displayedPerson...
}
}
In the storyboard, highlight the view controller you want to use a custom class for, and in the Custom Class field, type the name of your subclass. If you've done it correctly, it should autocomplete for you.
I have a UIView with a TableView and a Button (Big Button). The TableView has a custom Cell. In this cell there is an "Add" button. I want to animate the first button when the user makes click on the Add button.
This is my schema:
This is my code:
class ProductsViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet var tableView: UITableView!
#IBOutlet var bigButton: UIButton! <- I WANT TO ANIMATE THAT BUTTON
}
ProductCell class
class ProductCell: UITableViewCell {
#IBAction func addProduct(sender: AnyObject) {
//I WANT TO ACCESS THE BIG BUTTON FROM HERE
}
}
Screen example of my app
I've tried to get the parent controller or the superview to get the IBOutlet but the app is crashing allways
Add block properties to your cells which lets them notify your view controller when they have been clicked. In your view controller block code, you can then access the big button.
See my answer to a similar question. Simply replace the switch example with your button. So replace UISwitch with UIButton.
How can I get index path of cell on switch change event in section based table view
So rather than have the cell try and talk to another cell/button, have the cell notify the controller which can then manage the big button changes.
Although I made a comment about using alternate methods you could also employ a strategy below based on updates to a property stored in the current view controller class. You could just as well use property observation on the ProductsViewController but I assume you'd like to keep OOP focused and reduce the size of your controller.
Subclass the ViewController
One could subclass an existing UIViewController and then create a property in the super class that deals with the value that was changed (row tapped). In that subclass you could then do some animation. Because you would be subclassing you continue to obtain all the benefits and methods defined in your existing controller. In your identity inspector point your Class to the new subclass and create any functional updates to your UI using animation.
class ProductsViewController:... {
var inheritedProperty:UIView = targetView {
willSet {newValue } // is the newValue
didSet {oldValue} //is the old value
}
}
class AnimatedProductsViewController:ProductsViewController {
override var inheritedProperty:UIView {
//do something interesting if the property of super class changed
willSet {newValue } // is the newValue
didSet {oldValue} //is the old value
//you might want to call this method like so
// didSet { animate(newValue) }
}
func animate (view: UIView){
//do animation routine using UIView animation, UIDynamics, etc.
}
}
Property Observation
Whenever the didSelectCell... method is called just set a value to the inheritedProperty. Then add the property observers (see sample code) and react when the property changes (maybe pass a reference to the view you want to animate).
For example: Within the property observer you can just take that view and pass it to your animator function (whatever is going to do the animation). There are many examples on SO of how to animate a view so just search for (UIView animation, UIDynamics, etc).
The normal benefits of separation are encapsulation of functionality and reuse but Swift also guarantees that each set of property observers will fire independently. You'd have to give some more thought to this as to its applicability in this use case.
Do all this things in your viewController
Add target Method to cell's add button in cellForRowAtIndexPath Method
Like This
cell.add.addTarget(self, action: "addProduct:", forControlEvents: UIControlEvents.TouchUpInside)
Define method
func addProduct(button:UIButton)
{
// do button animation here
}