Learning with Swift and I've been at this all day with little progress:
Need to know when an item in NSCollectionView is selected. The end goal is to get the item to highlight and to be able to delete it from the collection with the delete key. My NSCollectionView is bound to an ArrayController to get content and send the selection indexes, so looks like I need to be watching the ArrayController for a selection change, but don't see any helpful delegate methods there. The prototype view has a single textfield.
I was following the obj-c examples here and elsewhere (found none in Swift), but a Swift NSCollectionViewItem doesn't have the setSelected method to override. It has a selected property.
How to get informed when an NSCollectionViewItem gets selected in Swift?
The most simple solution is to override the selected property and react for example whenever it is set:
class CollectionSonaViewItem: NSCollectionViewItem {
override var isSelected: Bool {
didSet {
// set background color to indicate selection
self.view.layer?.backgroundColor = (isSelected ? NSColor.blue.cgColor : NSColor.clear.cgColor)
// do more stuff
}
}
From there on you can send a notification or call a function in your collection view class, its delegate or whatever required.
Related
I am a beginner learning Swift and trying to build a search page with Swift. In my search page of the app, I have added two Views in my storyboard with one View above the other.
The upper View contains a Collection View where I have two prototypes of collection view cells. The first type of the cells has Label. The second type of the cells has TextField.
The other View on the bottom half of the screen contains a dynamic Table View where I have a list of items that can be selected. Each row of the table view cells has a selection item.
So, when I tap on a table view cell, the selection item will appear in the collection view. If I type a keyword in the TextField in the collection view, table view reloads and shows all the selection items that has the keyword, so I can tap and add an item to the collection view.
I would like to keep adding by typing a keyword after I tap on a searched item in the table view. So, I made the first cell showing selected items with labels and the second cell that has the TextField separated into two sections of the collection view. So, I only reload the first section (without TextField) for each selection. But somehow the keyboard automatically resign whenever I tap on the table view cell to add an item to the collection view.
Is there any way I can keep the keyboard up even when I tap on the tableview cells?
The keyboard also resigns when I tap the collection view cells.
I would appreciate your advice. Thanks.
I hope you are having a good day.
You can try calling this method on the UITextField you would like to show the keyboard for (maybe call it after the user taps on the UITableViewCell):
textField.becomeFirstResponder()
where "textField" is the variable name of your UITextField.
Please let me know if this fixed your issue.
Edit #1
Hello! Since my previous solution did not achieve your intended behavior. There is another solution in my mind, however I have not tried it before.
As an introduction to the concept of delegation, there is a method created by Apple called "textFieldShouldEndEditing" which is called by Apple whenever any keyboard will disappear on any text field.
This method is created by Apple, but you can override it (i.e. customize it) to suit your needs and tailor its behavior.
To override this method you have to assign your class as the delegate of UITextField by adding UITextFieldDelegate to your class definition as follows:
class YourClassName: UIViewController, UITextFieldDelegate { }
Now you have to set your class as the delegate by saying textField.delegate = self For every UITextField you create in your collection views
You then can re-create the method we discussed earlier in your class:
func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
//let's implement it the next steps, but for now, let's return true.
return true
}
Now instead of Apple calling their version of the method, they will call yours.
You then can create a variable in the top level of your class (I will let you know where this will be helpful later), and "maybe" name it as:
var isCellBeingClicked = false
Now upon clicking on a cell, make this variable true, I believe you are using the method didSelectRowAt (but you could be using any other method which is fine):
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
[...]
isCellBeingClicked = true
[...]
}
Now back to our customized method textFieldShouldEndEditing mentioned in step 3. You can add this implementation:
func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
//If a cell is being clicked right now, please do not dismiss the keyboard.
if isCellBeingClicked {
isCellBeingClicked = false //reset the value otherwise the keyboard will always be there
return false
}
else { return true }
}
Please let me know if this fixes your issue.
Best regards
I am fairly new at coding in swift and I've been trying to find a solution to my problem for the past couple days, and am not able to.
I have a class named userData with various properties:
class UserData {
var name: String
var age: Int
var credits: Int = 1
...
init(name: String, age: Int) {
self.name = name
self.age = age
}
}
Inside the viewController.swift I have declared an object of this class:
...
var user = UserData(name: "testing", age: 5)
...
Inside the same viewController I have a UITableView with a few UITableViewCells. In every cell there is a UIStepper
Using the UIStepper from a cell I want to increment or decrement the property credits of my object user that sits inside the viewController.swift, and do that from within the tableViewCell.swift file
From what I can find, I think I should use a delegate but I can figure out how to implement it.
More information:
Pardon the art work, I am not an artist...
The user has a set amount of ants available to work (this number is a property of my object user). There is also a property for the amount of ants currently working ('ants used' in my screen shot).
At first, the white label on top says '0/5' (Meaning the user has 5 available ants to work but none are currently working).
When the user increments the stepper for 'scavenger ants', the white label on top should say '1/5' (Meaning that there is currently 1 ant working out of 5 that are available).
What I want to do, is that when the user clicks on a stepper, the user's property for the 'ants currently working' increments or decrements appropriately.
Thank you
Set that logic up in the view controllers' cellForRowAt.
When setting up the cell, you can add a function inside your view controller as the target every-time the UIStepper value changes:
// inside cellForRowAtIndexPath:
cell.addTarget(self, action: #selector(doSomething(sender:), for: .valueChanged)
Inside doSomething you set up the logic for updating your model.
func doSomething(sender: UIStepper) {
// do stuff here
}
Edit with an example of the delegate pattern which would be a better solution, for future readers.
First create a protocol:
protocol StepperCellDelegate {
func didChangeValueForStepper(inCell: Cell, whateverInfoYouWantHere:...)
func otherUsefulFunctions(...)
}
In your cell class, set a target/action for when your value is changed:
// inside the cell's initialization (`init(style:reuseIdentifier:)`
self.addTarget(self, action: #selector(valueChanged(sender:), for: .valueChanged)
Your cell also needs a delegate property:
weak var stepperCellDelegate: StepperCellDelegate?
doSomething would look something like this:
func valueChanged(sender: UIStepper) {
stepperCellDelegate?.didChangeValueForStepper(inCell: self, ...)
}
Your ViewController will implement the protocol
extension MyViewController: StepperCellDelegate {
func didChangeValueForStepper(inCell: Cell, whateverInfoYouWantHere:...) {
// implementation here
}
func otherUsefulFunctions(...){
// implementation here
}
}
And inside cellForRowAtIndexPath set itself as the delegate:
// inside cellForRowAtIndexPath:
cell.stepperCellDelegate = self
Delegation is the proper way of handling this.
That UItableviewCell — both appear to be similar —
should expose a protocol with a set of methods
that the UIViewController can implement. Methods are
triggered when you tap on the UIStepper widget.
Best to stick to this methodology, and reuse it everywhere. Makes
things manageable loosely coupled.
I am creating a user profile screen which displays user details using MVC architecture.
I have UserProfileViewController where I will add the view dynamically based on whether user is in edit mode or normal mode.
When user is in normal mode - I load the normalView(Which I designed with separate xib) with labels to display the user details from the model.
When user in edit mode - I load the editView (Which I designed with separate xib) with textFields prepopulated with the value from the model.
I get the user details from the service call and update the model.
Now, when in edit view - How do I make textFieldDelagate comes to UserProfileViewController not the editView class?
And I need to validate and update the model when user end the editing of the field.
How do I do that?
Please provide if have any example or reference. I have searched but didn't get correct answer to solve my issue.
In your editView, add these lines of code,
class EditView {
public weak var textFieldDelegate: UITextFieldDelegate?
}
Then in awakeFromNib if EditView is subclass of UIView or in viewDidLoad if ViewController, filter all textFields and set their delegate as below,
yourMainView.subviews.filter({ $0 is UITextField}).forEach { view in
(view as? UITextField)?.delegate = self.textFieldDelegate
}
Now in UserProfileViewController add this conformance,
extension UserProfileViewController: UITextFieldDelegate {
func textFieldDidEndEditing(_ textField: UITextField) {
// TextField editing done
}
}
finally, when you are instantiating editView in UserProfileViewController, set its delegate to self like this,
editView.textFieldDelegate = self
I'm trying to observe a change to the selection of an NSPopUpButton in Swift 4. In my view controller's viewDidLoad() I've set up the observation token to observe the selectedItem property of the NSPopUpButton
override func viewDidLoad() {
super.viewDidLoad()
observation = observe(\.myPopUpButton.selectedItem) {
objectToObserve, change in
if change.kind == NSKeyValueObservedChange.Kind.setting {
// code to execute goes here
}
}
I set a breakpoint on the line where observation is set to determine that the token is being configured with the correct key path. I also set a break inside the closure to see when it is executed. When I change the selection of the NSPopUpButton, the closure does not execute.
selectedItem is of type, NSMenuItem?, so my suspicion is that I can't set an observation on an optional property. But I can't find anything in Apple's documentation that states whether or not that is the case and I'm not sure how I would go about verifying it for myself.
So I have sort of a primary question along w/ some followups:
Can I observe an optional property in Swift 4.1?
If so, how can I troubleshoot this, what am I doing wrong?
If not, how can I go about trying to monitor the state of the NSPopUpButton?
Troubleshoots that I've already tried...
added #objc dynamic to the my myPopUpButton declaration
Many properties of many AppKit objects are not KVO-compliant. Unless the documentation specifically says the property is compliant, you should assume it's not compliant. NSPopUpButton's selectedItem property is non-compliant.
The easiest way to be notified that the pop-up button's selected item changed is to set the button's target and action:
override func viewDidLoad() {
super.viewDidLoad()
myPopUpButton.target = self
myPopUpButton.action = #selector(popUpButtonDidFire(_:))
}
#IBAction private func popUpButtonDidFire(_ sender: Any) {
// code to execute goes here
}
Note that if you're creating the pop-up button in a storyboard or xib, you can wire it to the popUpButtonDidFire method by control-dragging from the pop-up button to the view controller.
As mentioned in the comments in macOS Cocoa Bindings and Swift's property observers are a very powerful way to observe values, even in prior Swift versions. An outlet is not needed.
Create a property and use the didSet observer
#objc dynamic var selectedObject : MyObject? {
didSet {
}
}
In Interface Builder in Bindings Inspector bind Selected Object to the target controller Model Key Path > selectedObject.
MyObject is the type of the represented object of the menu item. If nothing is selected selectedObject is nil. You can bind also Selected Index, Selected Tag or Selected Value (but not simultaneously).
The problem: HIGHLIGHT vs SCROLLING
My buttons inside the cell where not getting highlighted when I lightly tap on them. I had to tap hard and for a long time to be able to see the tap state of the button.
So I did this in order to set the delaysContentTouches to false (I didn't manage other way to do it) inside viewDidLoad():
for index in tableView.subviews {
if (index.isKindOfClass(UIScrollView)) {
let scrollViewFound = index as! UIScrollView
scrollViewFound.delegate = self
scrollViewFound.delaysContentTouches = false
scrollViewFound.canCancelContentTouches = true
scrollViewFound.scrollEnabled = true
}
}
This way the buttons highlight correctly but then I cannot scroll the table up or down, unless I start dragging from one of the empty cells --> userInteractionEnable = false in the empty cells
What I need:
To be able to highlight the buttons but also to scroll the table.
Is it even possible to have both, scrollable view and highlighted buttons?
What I have tried
I tried calling this function:
func touchesShouldCancelInContentView(view: UIView) -> Bool {
print("touchesShouldCancelInContentView happening---------")
return true
}
Which never gets called. I tried overriding But it gives an error:
Method does not override any method from its superclass
Which is weird, because UITableViewController inherits from UIScrollView. I also tried adding UIScrollViewDelegate to the class definition, but of course it gives another error that this is redundant.
Extra Information
The class is declared like this:
class Settings: UITableViewController, UITextFieldDelegate { ...
The tableView is made of Static Cells
The cells:
Some are empty: where UserInteractionEnable = false
Some have buttons with text field: I want these buttons to get highlighted. UserInteractionEnable = true. The button action is called by .TouchUpInside
Some have labels and a check image: Their action gets called in didSelectRowAtIndexPath which will change the labels colour and check images
Maybe it is relevant to say that when user clicks on any cell didSelectRowAtIndexPath it will
call a function to dismiss the keyboard.
You tried to subclass the wrong class, that's why it doesn't work. You have to subclass the UITableView class itself, and not the UITableViewController.
Can you try the following ?
- First
Subclass the TableView class in order to override the touchesShouldCancelInContentView function.
class UIDraggableTableView: UITableView {
override func touchesShouldCancelInContentView(view: UIView) -> Bool {
if (view.isKindOfClass(UIButton)) {
return true
}
return super.touchesShouldCancelInContentView(view)
}
}
- Second
In your TableViewController class, when viewDidLoad() is called, append the following right after super.viewDidLoad():
self.tableView = DraggableTableView()
This should solve your issue.
Part of this answer was taken from this StackOverflow post.