I have a document window that contains a number of NSView subclasses, switched between using a tab control. Each of the subclasses, and the window's ViewController, support different user actions accessed through menu items tied to the First Responder.
I'd like to perform a segue from one of those views in response to a menu item. However, NSView does not support performSegueWithIdentifier, it appears to be something that is part of NSViewController alone.
Can someone suggest a way around this? I have seen suggestions to pass the VC into the views, but I am not clear how to do that. Or perhaps there is a better way?
view.containingController.performSegue()
note: you have to add containingController to your views
I WOULD add the viewController to the responder chain and then make containingController a computed property in an extension!
e.g. add vc as responder:
override func awakeFromNib() {
super.awakeFromNib()
self.nextResponder = self.view
for subview in self.view.subviews {
subview.nextResponder = self
}
}
e.g. containingController in extension
extension NSView {
var containingController: NSViewController? {
get {
while(self.nextResponder != nil) {
if(self.nextResponder is NSViewController) {
return self.nextResponder
}
}
return nil
}
}
}
You could do that (see Daij-Djan's answer), however it is not what I would recommend, since a hypothetical programmer who will be using your code, but is not familiar with it (let's say, you in a year :) ) might be caught by surprise by such behaviour.
I would recommend you to add a delegate (conforming to your custom protocol, let's call it MyViewDelegate) to your NSView with a method like viewRequiresToPerformTransition(view: YourViewSubclass). Then you implement this method (more generally, you conform to MyViewDelegate protocol) in your view controller and inside its implementation perform any segue you want.
Related
Description
I am trying to use NSSegmentedControls to transition between Child ViewControllers. The ParentViewController is located in Main.storyboard and the ChildViewControllers are located in Assistant.storyboard. Each ChildViewController has a SegmentedControl divided into 2 Segments and their primary use is to navigate between the ChildViewControllers. So they are set up as momentaryPushIn rather than selectOne. Each ChildViewController uses a Delegate to communicate with the ParentViewController.
So in the ParentViewController I added the ChildViewControllers as following:
/// The View of the ParentViewController configured as NSVisualEffectView
#IBOutlet var visualEffectView: NSVisualEffectView!
var assistantChilds: [NSViewController] {
get { return [NSViewController]() }
set(newValue) {
for child in newValue { self.addChild(child) }
}
}
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
addAssistantViewControllersToChildrenArray()
}
override func viewWillAppear() {
visualEffectView.addSubview(self.children[0].view)
self.children[0].view.frame = self.view.bounds
}
private func addAssistantViewControllersToChildrenArray() -> Void {
let storyboard = NSStoryboard.init(name: "Assistant", bundle: nil)
let exampleChild = storyboard.instantiateController(withIdentifier: "ExampleChild") as! ExampleChildViewController
let exampleSibling = storyboard.instantiateController(withIdentifier: "ExampleSibling") as! ExampleSiblingViewController
exampleChild.navigationDelegate = self
exampleSibling.navigationDelegate = self
assistantChilds = [exampleChild, exampleSibling]
}
So far so good. The ExampleChildViewController has an NSTextField instance. While I am in the scope of the TextField, I can trigger the action of the SegmentedControls. Its navigating forward and backward as it should. But once I leave the scope of the TextField I can still click the Segments, but they are not triggering any action. They should be able to navigate forward and backward even if the TextField is not the current "First Responder" of the application. I think I am missing something out here, I hope anyone can help me with this. I know the problem is not the NSSegmentedControl because I am seeing the same behavior with an NSButton, which is configured as Switch/Checkbox, in the SiblingViewController. I just don't have any idea anymore what I am doing wrong.
It`s my first time asking a question myself here, so I hope the way I am doing is fine for making progress with the solution. Let me know if I can do something better/different or if I need to provide more information about something.
Thanks in advance!
Additional Information
For the sake of completeness:
The ParentViewController itself is embedded in a ContainerView,
which is owned by the RootViewController. I can't imagine this does
matter in any way, but this way we are not missing something out.
I am actually not showing the navigation action, because I want to
keep it as simple as possible. Furthermore the action is not problem,
it does what I want it to do. Correct me if I am wrong with this.
Possible solutions I found while researching, which did not work for me:
Setting window.delegate of the ChildViewControllers to NSApp.windows.first?.delegate
Setting the ChildViewController to becomeFirstResponder in its func viewWillAppear()
visualEffectView.addSubview(self.children[0].view, positioned: NSWindow.OrderingMode.above, relativeTo: nil)
Related problems/topics I found while researching:
Basic segmented control not working
Adding and Removing Child View Controllers
NSSegmentedControl - Odd appearance when placed in blur view
How to set first responder to NSTextView in Swift?
How to use #selector in Swift 2.2 for the first responder
Accessing methods, actions and/or outlets from other controllers with swift
How to use Child View Controllers in Swift 4.0 programmatically
Container View Controllers
issues with container view
Control a NSTabViewController from parent View
How to detect when NSTextField has the focus or is it`s content selected cocoa
SOLUTION
let parentViewControllerInstance = self.parent as! ParentViewController
segmentedControl.target = parentViewControllerInstance
In my case I just had to set the delegate as the target of the sendAction method.
Background
Ok, after hours of reading the AppKit Documentation I am now able to answer my own question.
First, debugging the UI showed that the problem was definitely not in the ViewHierarchy.
So I tried to think about the nature of NSButton and NSSegmentedControl. At some point I noticed that both are subclasses of NSControl.
class NSSegmentedControl : NSControl
class NSButton : NSControl
The AppKit Documentation says:
Discussion
Buttons are a standard control used to initiate actions within your app. You can configure buttons with many different visual styles, but the behavior is the same. When clicked, a button calls the action method of its associated target object. (...) You use the action method to perform your app-specific tasks.
The bold text points to the key of the solution – of its associated target object. Typically I define the action of an control item like this:
button.action = #selector(someFunc(_:))
This causes the NSControl instance to call this:
func sendAction(_ action: Selector?, to target: Any?) -> Bool
Parameter Description from the documentation:
Parameters
theAction
The selector to invoke on the target. If the selector is NULL, no message is sent.
theTarget
The target object to receive the message. If the object is nil, the application searches the responder chain for an object capable of handling the message. For more information on dispatching actions, see the class description for NSActionCell.
In conclusion the NSControl instance, which was firing the action method (in my case the NSSegmentedControl), had no target to send its action to. So it was only able to send its action method across the responder chain - which obviously has been nil while the first responder was located in another view.
I am developing a Mac app using storyboards. I have a window that presents an NSViewController as its contents, which contains a "container view controller" that embeds an NSSplitViewController.
The expected behaviour is for the NSSplitViewController to be part of the responder chain, such that a menu item that triggers the toggleSidebar action on the first responder actually collapses the item of the NSSplitViewController that's marked as a sidebar.
However, this simply does not happen and the menu item remains disabled. So my question is, how can-I get the NSSplitViewController to be part of the responder chain?
I noticed that maybe some of these solutions have worked, but i adapted a more general purpose answer from https://stackoverflow.com/a/30938725/6938357.
I made an extension on NSViewController to look for supplemental targets. Works on NSSplitViewController as well as any general NSViewController with child(ren).
extension NSViewController {
open override func supplementalTarget(forAction action: Selector, sender: Any?) -> Any? {
if let target = super.supplementalTarget(forAction: action, sender: sender) {
return target
}
for child in children {
var target = NSApp.target(forAction: action, to: child, from: sender) as? NSResponder
if target?.responds(to: action) == false {
target = child.supplementalTarget(forAction: action, sender: sender) as? NSResponder
}
if target?.responds(to: action) == true {
return target
}
}
return nil
}
}
If you only want this to search on a single view controller, put this implementation there instead. This extension applies to all NSViewControllers and its subclasses.
Check out the nextReponsder property of NSResponder. This property defines the responder chain. It's normally set automatically to follow the responder change defined by the Cocoa framework, but you can alter it to insert/skip/divert the chain in a different direction.
For example, at some point (don't ask me when), Cocoa started including the window's controller in the responder chain. So that my apps work consistently on all versions of macOS, I'll include code like this my window's controller:
- (void)windowDidLoad
{
// Sent when the controller's window has been loaded from the nib
[super windowDidLoad];
NSWindow* window = self.window;
// Make sure this window controller is in the responder chain
NSResponder* nextResponder = window.nextResponder; // get our window's next responder
if (nextResponder!=self)
{
// running earlier OS X that does not include the window controller in the chain: patch us in
self.nextResponder = nextResponder;
window.nextResponder = self;
}
-windowDidLoad, -viewDidLoad, and -awakeFromNib are all good places to adjust the responder chain so they include, or exclude, whatever objects you want.
I ended up getting this to work (in Swift 4) by adding my view controller to the window delegate. After that, my view controller was part of the responder chain (which made application menu items work in my view controller).
//Step 1: Add NSWindowDelegate to the controller
class MyViewController: NSViewController, NSWindowDelegate{
override func viewDidLoad() {
super.viewDidLoad()
//Step 2: Add the view controller to the window delegate
if let window = NSApp.windows.first{
window.delegate = self
}
}
}
I hope that helps someone else. :)
The main ViewController is embedded in a UINavigationController subclass, and the VC has a subview that is loaded from a nib. The subview is called MenuView, and contains UIButtons that will link to other VCs.
To keep my main ViewController less unruly, I have put all these buttons into a subview that loads from a nib that animates the menu opening and closing.
However, I would like to present other view controllers from these, sometimes "Modally", sometimes "Show". What I have done seems to work, but I just want to know if this is alright, or if I have caused some unwanted effects that I'm unaware of (like a strong reference cycle that would cause a memory leak, or something). Or is there a better way to do this?
Some code:
In MenuView.swift
class MenuView: UIView {
var navigationController = CustomNavigationController()
func combinedInit(){
NSBundle.mainBundle().loadNibNamed("MenuViewXib", owner: self, options: nil)
addSubview(mainView)
mainView.frame = self.bounds
}
#IBAction func optionsAction(sender: AnyObject) {
self.navigationController.performSegueWithIdentifier("presentOptions", sender: self)
}
In ViewController.swift
menuView.navigationController = self.navigationController as! CustomNavigationController
Short answer: No, it is not alright to access a view controller from within some view in the hierarchy, because that would break all the MVC rules written.
UIView objects are meant to display UI components in the screen and are responsible for drawing and laying out their child views correctly. That's all there is. Nothing more, nothing less.
You should handle those kind of interactions between views and controllers always in the controller in which the view in question actually belong. If you need to send messages from a view to its view controller, you can make use of either the delegate approach or NSNotificationCenter class.
If I were in your shoes, I would use a delegate when view needs some information from its view controller. It is more understandable than using notification center as it makes it much easier to keep track of what's going on between. If the view controller needs some information from a view (in other words, the other way around), I'd go with the notification center.
protocol MenuViewDelegate: class {
func menuViewDidClick(menuView: MenuView)
}
class MenuView: UIView {
var weak delegate: MenuViewDelegate?
#IBAction func optionsAction(sender: AnyObject) {
delegate?.menuViewDidClick(self)
}
}
Let's look at what's going on at the view controller side:
class MenuViewController: UIViewController, MenuViewDelegate {
override func viewDidLoad() {
...
self.menuView.delegate = self
}
func menuViewDidClick(menuView: MenuView) {
navigationController?.performSegueWithIdentifier("presentOptions", sender: self)
}
}
For more information about communication patterns in iOS, you might want to take a look at this great article in order to comprehend how they work.
First of all I have to say I am really new to swift and Objective C.I am learning them by myself.
I have a question for this code
I have a delegate in my SettingViewController called "settingsViewControllerFinished" and it pass the whole controller as a variable.
the code like this:
in my SettingViewController.swift
protocol SettingViewControllerDelegate: class {
func settingsViewControllerFinished(settingsViewController: SettingsViewController)
}
#IBAction func close(sender: AnyObject) {
dismissViewControllerAnimated(true, completion: nil)
self.delegate?.settingsViewControllerFinished(self)
}
I am confused.What did you mean if you pass the whole controller as a variable?(maybe the question is silly for you)
in my viewController:
func settingsViewControllerFinished(settingsViewController: SettingsViewController)
{
self.brushWidth = settingsViewController.brush
self.opacity = settingsViewController.opacity
self.red = settingsViewController.red
self.green = settingsViewController.green
self.blue = settingsViewController.blue
}
I guess the reason is:I pass everything in SettingViewController to ViewController so that I could use the variables in SettingViewController.
Am I rihgt?
Generally you are correct, yes: passing the SettingViewController back to its delegate enables the original caller to not have to keep a reference to the created and shown SettingViewController since the delegate method sends the relevant information along already.
But there is more: In some cases of delegates this style is useful for something different. Imagine a click handler consisting of a function func somethingGotClicked(sender:YourSenderType). If your class creates multiple instances of YourSenderType and shows them at the same time registering itself as their delegate there would be no way to know which one got clicked if there was no sender parameter. In some func somethingGotClicked() you would not know which one got clicked. That capability is often needed when showing multiple UITableView or UICollectionView is one single view with one single instances set as their delegate.
I have been playing with the concept of the parent/child view delegation for a few days now, and currently understand how to feed data from parent to child. However, now, I want a button in the parent (main VC) to reload the data presented in the child VC.
I'm trying to delegate a method that is activated in the child VC's class but is activated in the parent's navigation controller. So that when I press the button, the delegated method in the child VC is performed; in my case, that method would be reload table. Why am I getting so many errors when trying to set up this simple delegation relationship?
My parent/container View is currently delegating a method to the child, so I have it set up from child -> parent. But I want to set it up from parent -> child. Pretty much I have:
struct Constants {
static let embedSegue = "containerToCollectionView"
}
class ContainerViewController: UIViewController, CollectionViewControllerDelegate {
func giveMeData(collectionViewController: CollectionViewController) {
println("This data will be passed")
}
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if segue.identifier == Constants.embedSegue {
let childViewController = segue.destinationViewController as! CollectionViewController
childViewController.delegate = self
}
}
FROM CHILD:
protocol CollectionViewControllerDelegate {
func giveMeData(collectionViewController: CollectionViewController)
}
class CollectionViewController: UIViewController {
var delegate:CollectionViewControllerDelegate?
override func viewDidLoad() {
super.viewDidLoad()
self.delegate?.giveMeData(self)
// Do any additional setup after loading the view.
}
I think my trouble is the fact that I'm declaring the child delegate in a prepareforsegue, so that was straight forward, but now I want the reverse delegation. How do I set that up so that I can use a child-method from the parent VC?
The child view controller has no business supplying other controllers with data. It should actually not even have any data fetching logic that is so generic it is also used by other controllers. You should refactor the data methods out into a new class.
This pattern is called Model-View-Controller, or MVC, and is a very basic concept that you should understand and follow. Apple explains it pretty well.
In general, to send data to from a controller to a detail controller, use prepareForSegue to set properties, etc. To communicate back to the parent controller, you use delegate protocols, but usually these are called when the detail controller is finished with its work and just reports the result up to the parent.
If you want to update the detail VC with new data (without dismissing it and with the parent not visible) you should not put the logic to update it into the parent. Instead, use the structure suggested above.