I am trying to update my firstVC "like Button" Status once the user enters the SecondVC and likes or unlikes the heart for the cell they entered. I've tried a ton of different ways today but none seem to work properly. Any help or ideas
Basically. The user can click on a cell, then gets directed to another view controller which they also can change the status of the like button in there. Once they return back to the mainVC I want the like button to display the change.
I'm wondering if I am suppose to save the cells data locally in the phone or just send variables back and forth to each view controller. But if I send variables back and forth, how do I send a variable back to the first VC to the specific cell and let it know that the cell like button is no longer liked. I hope I make sense. Thank you all in advance. Still new to swift here :)
I think you can use the delegate pattern
protocol ViewController2Delegate: class {
func buttonStatusDidChange(_ viewController2: ViewController2, to status: Bool)
}
Add this property to the second view controller:
weak var delegate: ViewController2Delegate?
When the button status change, call:
delegate?.buttonStatusDidChange(self, to: true)
Make the first view controller conform to the protocol:
extension ViewController1: ViewController2Delegate {
func buttonStatusDidChange(_ viewController2: ViewController2, to status: Bool) {
// change the button according to the status
}
}
Related
I have a problem understanding what I can do with the default Back BarButtonItem and how I can instigate a rewind.
The following shows a simplified layout. I embed a ViewController in a Navigation controller and add a BarButtonItem ("Show") and connect to a second VC. This adds the "Back" button to the second controller as shown below.
In the first VC I will show the user some details, in the second VC greater details will be shown. With the show button and the default back button the user can easily navigate back and forth with expected behavior.
My problem comes in that the user will be allowed to modify the "More Details Here" and I will need to pass that to the first VC after the user unwinds back.
I cannot control-drag from the Back to the Exit icon but I have determined I can do this with a "Save" button on the navigation bar as shown. (First dragging an Navigation Item to the top, then the BarButtonItem) then control-drag to Exit icon.
With the Save button, I can initiate a segue unwind and capture the changes back in my first VC with code like the following.
#IBAction func unwindFromSecondVC(_ sender: UIStoryboardSegue) {
if sender.source is AddCharacterViewController {
if let senderVC = sender.source as? SecondViewController {
details = senderVC.newDetails
}
}
}
This creates a problem when the user makes a change and then clicks the back button thereby loosing the changes.
My preferred solution would be to have the back button initiate a segue and transfer the changes. But this does not appear to be possible. My second solution would be to have the back button notice a transfer has not been made and stop the unwind seque. Neither approach appears possible based on my research.
How should I best handle this problem while giving the user the common Back navigation?
If you want to save any changes the user has made in the second VC, you could create a SecondVCDelegate:
protocol SecondVCDelegate : class {
func detailsDidChange(newDetails: String)
}
In SecondVC, declare a delegate property:
weak var delegate: SecondVCDelegate?
And whenever the details change (the text field's value changed, or whatever event happened), you call
delegate?.detailsDidChange(newDetails: newDetails)
In FirstVC.prepareForSegue, you should set self as the delegate of SecondVC:
if let vc = segue.destination as? SecondVC {
vc.delegate = self
}
// ...
extension FirstVC : SecondVCDelegate {
func detailsDidChange(newDetails: String) {
details = newDetails
}
}
This way, whenever the newDetails change, FirstVC will be notified.
If you just want to notify FirstVC when the user leaves SecondVC, you could instead call the delegate in SecondVC.viewWillDisappear or a method like that.
I have a UIViewController that implements UITableViewDelegate, UITableViewDataSource and that contains a UITableView as a member variable. When a user click on one of the rows of that table, the app performs a storyboard segue to open the detail view controller. That detail view controller of course has a button in the top left of the screen that is the "back" button to go back up to the UIViewController with the UIViewTable.
So, suppose that I want to programmatically "click" that back button. How exactly would I do that in swift? This is the most recent version of swift (swift 4?) in XCode 10.1.
UPDATE:
So here is how I solved this. As the answers below show, it is possible to use self.navigationController?.popViewController(animated: true) to just return to the previous view controller. What I discovered I also wanted to do, however, was to call a specific method in that view controller so that it executed a certain behavior once it got shown. It turns out that is also possible, but in my case it was a bit tricky, since that prior view controller was actually a UITabBarController. Therefore I had to get the ViewController that I was interested in from the UITabBarController. I did it like this:
let numvc = navigationController!.viewControllers.count
let tvc:UITabBarController = navigationController!.viewControllers[numvc-2] as! UITabBarController
let my_vc: MyCustomVC = tvc.viewControllers![0] as! MyCustomVC
my_vc.some_function()
Here of course MyCustomV is my custom view controller class and some_function() is the method I want to call on that class. Hope this helps someone.
When You run a segue you perform a "pushViewController" method to the next view, so if you want to go back to the previous view programmatically you just have to do is pop the last view like so:
self.navigationController?.popViewController(animated: true)
UPDATE
You just need the if statement if you have multiple segues from that viewController, if not, you can delete and just cast the next view as you wish and set the properties, let the autocomplete write the *prepare(for segue... * method for you, so You don't run into any problems
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "yourSegueName" {
let destinationVC = segue.destination as! CustomViewController
destinationVC.labelExample.text = "Some text I'm sending"
}
}
Are you sure you need to "click" the button?
If all you need is to dismiss details view controller, you can just call navigationController?.popViewController(animated: true)
Or if you want to deal directly with button, you can tell it to send its actions: backButton.sendActions(for: .touchUpInside)
Or if you absolutely need to show button clicking animation, then you will need something like this (you should play and choose suitable delay):
backButton.isHighlighted = true
DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.3) {
backButton.isHighlighted = false
backButton.sendActions(for: .touchUpInside)
}
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.
Sorry for the newbie question but i am really stuck.
I have a UIViewController and 4 tableviews in an app. When i click on a button on the UIViewcontroller it segues to a UITableviewController called "Beach". When the user clicks on a cell of the table, it segues back to the UIViewController and displays the selected cells title as the buttons title. The problem that i am having is when i click on a nother button to a tableview and then clicks on the cell, the previous buttons title sets back to the previous title.
i have a prepare for segue function in the tables view controllers and this returns the selected table title (named : Titleoftable) to the main VC which, the strings.
the way i am currently doing it is to make a NSUserDefault below but the problem still remains the same - The value changes top "" every time i click on another table V---
let path = tableView.indexPathForSelectedRow
let cell = tableView.cellForRowAtIndexPath(path!)
let persistenceStoreKey = "MyStringKey"
let stringToStore = "\((cell?.textLabel?.text!)!)"
// Store data
NSUserDefaults.standardUserDefaults().setObject(stringToStore, forKey: persistenceStoreKey)
NSUserDefaults.standardUserDefaults().synchronize()
// Get data
let myStringt = NSUserDefaults.standardUserDefaults().stringForKey(persistenceStoreKey)
destination.textOfBeach = (myStringt)!
destination.isBeachSelected = true
}
I have been stuck on this problem for ages now! PLEASE HELP!!
PS- I am using swift-2 and Xcode7
Make sure that you are not pushing a new ViewController after you click on the tableview's cell. It gives me the impression that it might be the case since you are seeing only the title of the last cell you pressed.. Make sure you actually pop the tableview's controller instead of pushing a new one.
If you want to keep using NSUserDefaults, you could just call
navigationController?.popViewController(animated: true)
in your cellSelection function, and read the defaults value in the viewWillAppear of the main ViewController.
override func viewWillAppear(_ animated: Bool) {
let userDefault = NSUserDefaults.standard()
if let beachSelection = userDefault.string(forKey: "BeachControllerSelection") {
textOfBeach = beachSelection
isBeachSelected = true
}
//same for the rest of the other table view's selections
}
I am new in iOS and storyboard and I need some advice on the possible ways of designing the architecture of the new app. I will have some data saved in the database and I will have a UIViewController page with just some buttons that have some names of some categories. When let's say 'All' is clicked or 'Business' is clicked, it will fetch data show according to that category to a UITableViewController.
Now I am confused on one part:
In story board is it allowed to create multiple segues from different buttons to the same ViewController Class? So if that is not allowed, do I have to create 6 different UITableViewController classes to make segues for 6 categories?
And if it is allowed to make segues from multiple buttons to a single UIViewController, how do I send a parameter in storyboard to make it realize that I clicked a specific button to go to the UIViewController.
Should I make a custom constructor in the UITableViewController which takes a parameter and I will initial that constructor from the other button click methods? So that it displays results in terms of category? Or is there a way storyboard does this more easily?
Sure, you can do that.
After creating all your buttons, control-drag from each button to the next view controller and create (for example) a "push" segue. Next, click on the segue graphic to select the segue. Switch to the Attributes inspector and give segue an identifier, like "All" or "Business". You can look at the segue's identifier in your -prepareForSegue: method to figure out which segue caused the transition, and hence which category to display.
I don't recommend that approach, though. There's no need to create half a dozen segues that all do exactly the same thing. I'd use an action that triggers a single segue instead:
Set the tag property of each button to a unique value so that you can differentiate between the buttons.
Add an action method to your first view controller (the one that manages the buttons) named something like -(IBAction)switchToCategoryFromButton:(id)sender.
Connect all the buttons to that single action.
Implement the action such that it looks at sender.tag to figure out which button was pressed, uses that to determine which category to load, and then triggers the one segue to the next view controller programmatically.
Having a single segue triggered by an action seems a lot neater than many segues. Code to do that might look like this:
- (IBAction)switchToCategory:(UIControl*)sender
{
// map the tapped button to a category
switch (sender.tag) {
case kAllButton: {
self.category = kAllCategories;
break;
}
case kBusinessButton: {
self.category = kBusinessCategory;
break;
}
default: {
self.category = kAllCategories;
break;
}
}
// start the segue
[self performSegueWithIdentifier:kCategorySegue sender:self];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
// tell the destination view controller what category to display
if ([segue.identifier isEqualToString:kCategorySegue]) {
[(NextViewController*)segue.destinationViewController setCategory:self.category];
}
}
Use
self.performSegueWithIdentifier("yourViewSegue", sender: sender) under your event for handling button's click like :
#IBAction func redButtonClicked(sender: AnyObject) {
self.performSegueWithIdentifier("redView", sender: sender)
}
redView is the segue Identifier .
You can use same function for your button event handling & can distinguish button touch by assigning them different tags.