I can display several table rows but when I tap one of those rows, the app crashes at tableView.setNumberOfRows(:)
I don't have any clue of what is going on. Any advise or tips are welcome. Thanks in advance.
I don't understand why this happens because at the initial setup this code runs without errors. I get this error only when I tap one of the table rows.
import WatchKit
import Foundation
class InterfaceController: WKInterfaceController {
#IBOutlet var tableView: WKInterfaceTable!
override func awake(withContext context: Any?) {
super.awake(withContext: context)
// Configure interface objects here.
loadTableData()
}
override func willActivate() {
// This method is called when watch view controller is about to be visible to user
super.willActivate()
}
override func didDeactivate() {
// This method is called when watch view controller is no longer visible
super.didDeactivate()
}
private func loadTableData() {
tableView.setNumberOfRows(Categories.NotLocalizedCategories.count, withRowType: "RowController")
for (index, category) in Categories.LocalizedCategories.enumerated() {
if let rowController = tableView.rowController(at: index) as? RowController {
rowController.rowLabel.setText(category)
}
}
}
override func table(_ table: WKInterfaceTable, didSelectRowAt rowIndex: Int) {
pushController(withName: "DetailInterfaceController", context: Categories.LocalizedCategories[rowIndex])
}
}
Apparently, either tableView or the context Categories.LocalizedCategories[rowIndex] is nil. Use the if let construct or the guard statement before passing the context.
This is happening because probably the DetailInterfaceController class, more precisely in the awake method, is being called super.awake, when doing this, the InterfaceController class will be instantiated again and the awake of this and everything inside is executed. Since the table reference for the storyboard is weak, its instance of the table will be null and then it will crash. One solution to this is to remove super.awake from the controllers you push.
Related
I've just started working on my first project for macOS and am having trouble setting up a NSTableView. When I run it the window will appear but there is nothing in it. I've made sure all the objects have the correct class in the identity inspector and can't seem to find what I'm doing wrong.
The goal of the app is to make a notes app. I want a tableView which displays the titles of all the notes in the database, in a single column, so when you click on the cell the note will then be displayed in the rest of the window.
Here's the code:
import Foundation
import AppKit
import SQLite
class NoteCloudVC: NSViewController {
// Declare an array of Note objects for populating the table view
var notesArray: [Note] = []
// IBOutlets
#IBOutlet weak var tableView: NSTableView!
// ViewDidLoad
override func viewDidLoad() {
super.viewDidLoad()
// set the tableViews delegate and dataSource to self
tableView.delegate = self
tableView.dataSource = self
//Establsih R/W connection to the db
do {
let path = NSSearchPathForDirectoriesInDomains(
.applicationSupportDirectory, .userDomainMask, true
).first! + "/" + Bundle.main.bundleIdentifier!
// create parent directory iff it doesn’t exist
try FileManager.default.createDirectory(
atPath: path,
withIntermediateDirectories: true,
attributes: nil
)
let db = try Connection("\(path)/db.sqlite3")
//Define the Notes Table and its Columns
let notes = Table("Notes")
let id = Expression<Int64>("ID")
let title = Expression<String>("Title")
let body = Expression<String>("Body")
/*
Query the data from NotesAppDB.sqlite3 into an array of Note objs
Then use that array to populate the NSTableView
*/
for note in try db.prepare(notes) {
let noteToAdd = Note(Int(note[id]), note[title], note[body])
notesArray.append(noteToAdd)
}
} catch {
print(error)
}
}
// viewWillAppear
override func viewWillAppear() {
super.viewWillAppear()
tableView.reloadData()
}
}
// NSTableViewDataSource Extension of the NoteCloudVC
extension NoteCloudVC: NSTableViewDataSource {
// Number of rows ~ returns notesArray.count
func numberOfRows(in tableView: NSTableView) -> Int {
return notesArray.count
}
}
// NSTableViewDelegate extension of the NoteCloudVC
extension NoteCloudVC: NSTableViewDelegate {
// Configures each cell to display the title of its corresponding note
func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
//configure the cell
if tableColumn?.identifier == NSUserInterfaceItemIdentifier(rawValue: "NotesColumn") {
let cellIdentifier = NSUserInterfaceItemIdentifier(rawValue: "NotesCell")
guard let noteCell = tableView.makeView(withIdentifier: cellIdentifier, owner: self) as? NotesCell else { return nil }
let note = notesArray[row]
noteCell.noteTitle.stringValue = note.title
return noteCell
}
return nil
}
}
// NotesCell class
class NotesCell: NSTableCellView {
// IBOutlet for the title
#IBOutlet weak var noteTitle: NSTextField!
}
I'm pretty familiar with UIKit so I thought the learning curve of AppKit would be a little better than SwiftUI, so if anyone could provide some guidance about where I've gone wrong that would be very much appreciated. Also if it will be a better use of my time to turn towards SwiftUI please lmk.
Here's the values while debugging:
It's reading the values from the table correctly, so I've at least I know the problem lies somewhere in the tableView functions.
The most confusing part is the fact that the header doesn't even show up. This is all I see when I run it:
Here are some images of my storyboard as well:
This is for an assignment for my software modeling and design class where my professor literally doesn't teach anything. So I'm very thankful for everyone who helps with this issue because y'all are basically my "professors" for this class. When I move the tableView to the center of the view controller in the story board I can see a little dash for the far right edge of the column but that's it, and I can't progress any further without this tableView because the whole app is dependant upon it.
So, it turns out that the code itself wasn't actually the problem. I had always used basic swift files when writing stuff for iOS so it never occured to me that I'd need to import Cocoa to use AppKit but that's where the problem lied all along. Using this code inside the auto-generated ViewController class that had Cocoa imported did the trick. Also I got rid of the extensions and just did all the Delegate/ DataSource func's inside the viewController class.
I want to prevent certain toolbar items from being removed by the user. They should still be movable, just not removable.
I tried creating a custom subclass of NSToolbar with a custom removeItem(at:) implementation, but it seems this method is not even called if the user drags an item out of the toolbar in the customization palette.
The delegate also doesn't seem to expose functionality for this.
How can I disable removal of certain NSToolbarItems?
I am not sure if you can prevent it from being removed but you can implement the optional toolbarDidRemoveItem method and insert the item that you don't want it to be removed back:
import Cocoa
class WindowController: NSWindowController, NSToolbarDelegate {
#IBOutlet weak var toolbar: Toolbar!
override func windowDidLoad() {
super.windowDidLoad()
toolbar.delegate = self
}
func toolbarDidRemoveItem(_ notification: Notification) {
if let itemIdentifier = (notification.userInfo?["item"] as? NSToolbarItem)?.itemIdentifier,
itemIdentifier.rawValue == "NSToolbarShowColorsItem" {
toolbar.insertItem(withItemIdentifier: itemIdentifier, at: 0)
}
}
}
Since it is not super critical if they are removed in case a private API call would stop working, I opted for the private API solution.
extension NSToolbarItem {
func setIsUserRemovable(_ flag: Bool) {
let selector = Selector(("_setIsUserRemovable:"))
if responds(to: selector) {
perform(selector, with: flag)
}
}
}
This works exactly as advertised.
I've tried, without success, respond to events such as windowWillClose() and windowShouldClose() inside NSWindowController (yes conforming to NSWindowDelegate).
Later, to my surprise, I was able to receive those events if I make my contentViewController (NSViewController) conform to NSWindowDelegate.
Unfortunately, later on, found out that view.window?.windowController is nil inside windowWillClose() or windowShouldClose(), code:
override func viewDidAppear() {
super.viewDidAppear()
self.view.window?.delegate = self
self.view.window?.windowController // not nil!
}
func windowWillClose(_ notification: Notification) {
self.view.window?.windowController // nil!!
}
func windowShouldClose(_ sender: NSWindow) -> Bool {
self.view.window?.windowController // nil!!
return true
}
After realizing that view.window?.windowController is not nil inside viewDidAppear() the next thing I thought was that Swift garbage collected the controller, so I changed viewDidAppear() in a way that creates another reference of windowController thus preventing garbage collection on said object, code:
var windowController: NSWindowController?
override func viewDidAppear() {
super.viewDidAppear()
self.view.window?.delegate = self
windowController = view.window?.windowController
}
func windowWillClose(_ notification: Notification) {
self.view.window?.windowController // NOT nil
}
func windowShouldClose(_ sender: NSWindow) -> Bool {
self.view.window?.windowController // NOT nil
return true
}
My hypothesis turned out to be correct (I think).
Is this the same issue that is preventing me from receiving those events inside NSWindowController?
Is there another way I can achieve the same thing without creating more object references?
In order to post code, I use the Answer option even though it is more of a comment.
I added in NSViewController:
override func viewDidAppear() {
super.viewDidAppear()
parentWindowController = self.view.window!.windowController
self.view.window!.delegate = self.view.window!.windowController as! S1W2WC. // The NSWC class, which conforms to NSWindowDelegate
print(#function, "windowController", self.view.window!, self.view.window!.windowController)
}
I get print log:
viewDidAppear() windowController Optional()
and notification is passed.
But if I change to
override func viewDidAppear() {
super.viewDidAppear()
// parentWindowController = self.view.window!.windowController
self.view.window!.delegate = self.view.window!.windowController as! S1W2WC
print(#function, "windowController", self.view.window!, self.view.window!.windowController)
}
by commenting out parentWindowController, notification don't go anymore to the WindowController…
Edited: I declared in ViewController:
var parentWindowController: NSWindowController? // Helps keep a reference to the controller
The proposed solutions are, in my opinion, hacks that can cause serious problems with memory management by creating circular references. You definitely can make instances of NSWindowController work as the window’s delegate. The proper way is to wire it up correctly in either code or in Interface Builder in Xcode. An example of how to do it properly is offered here.
If the delegate methods are not called is because the wiring up is not done correctly.
Another thing that must be done in Swift is when you add the name of the NSWindowController subclass in Interface Builder in Xcode is to check the checkbox of Inherits from Module. If you fail to do this, none of your subclass methods will be called.
suppose I have two viewcontroller called A and B. In my viewcontroller B I have a tableview in it. When I selected a cell in my tableview, I want to pass that information back to A.
I have a dictionary that is of the following:
myData = [String: DataModel]
where DataModel takes the form of
struct DataModel{
var address = ""
var name = ""
}
I want to send the selected cell's key in B back to A. How should I go about doing that?
thanks for your help
Add this before class BViewController:
protocol ClassBViewControllerDelegate: class {
func didSelectTableViewCell(onRow row: Int)
}
Create a delegate property in BViewController:
weak var delegate: ClassBViewControllerDelegate?
Implement tableView delegate method tableView(_:didSelectRowAt:)
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath:NSIndexPath) {
let row = indexPath.row
delegate?.didSelectTableViewCell(onRow: row)
}
Tell ClassAViewController that its conforms to ClassBViewControllerDelegate as such:
class ClassAViewController: UIViewController, ClassBViewControllerDelegate {
Bind ClassAViewController and ClassBViewController at an appropriate place in ClassAViewController such a, for instance, prepareForSegue:sender:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "SegueIdentifierXYZ" {
if let vc = segue.destination as? ClassBViewController {
vc.delegate = self
}
}
}
Use delegate method didSelectTableViewCell(onRow row: Int) of delegate contract ClassBViewControllerDelegate in ClassAViewController:
func didSelectTableViewCell(onRow row: Int) {
print("Selected table view row is:", row)
}
Using completion block or by using delegates you can achieve this.
Using blocks you can code like this:
In your B VC create one property for completion block.
var cellSelectionCallBackHandler: ((DataModel, Int) -> Void)?
Set the cellSelectionCallBackHandler property from VC A.
VCObjectB.cellSelectionCallBackHandler = { (data, index) in
// Use your data here
}
From VC B call the completion handler on selecting cell like this
cellSelectionCallBackHandler?(yourData, index)
Any doubt plz comment.
A delegate method can be used to achieve it. The place/method where you call to dismiss B call the delegate. You can implement this delegate in A.
You can also have a singleton dataHandler class, where you can set and get required properties and can access it from anywhere within your project.
I am trying to build an NSCollectionView filled with multiple editable TextViews. (OS X app in Swift.) My subclass of NSCollectionViewItem is called NoteViewItem. I am trying to have the program detect when one of the TextView has changed. I tried using both controlTextDidChange and textDidChange in the NoteViewItem's delegate with test print statement to see which would work. ControlTextDidChange did nothing; textDidChange recognized a change happened, so I went with that.
The problem is that textDidChange appears to point to a different NoteViewItem than the one that was shown on screen in the first place. It wasn't able to recognize the variable (called theNote) set in the original NoteViewItem; when I ask NoteViewItem to print String(self), I get two different results, one while setting the initial text and one in textDidChange. I'm wondering if I've set up my delegates and outlets wrongly. Any thoughts on why my references are off here?
Here's my code for NoteViewItem:
import Cocoa
class NoteViewItem: NSCollectionViewItem, NSTextViewDelegate
{
// MARK: Variables
#IBOutlet weak var theLabel: NSTextField!
#IBOutlet var theTextView: NSTextView!
var theNote: Note?
{
didSet
{
// Pre: The NoteViewItem's theNote property is set.
// Post: This observer has set the content of the *item's text view*, and label if it has one.
guard viewLoaded else { return }
if let theNote = theNote
{
// textField?.stringValue = theNote.noteText
theLabel.stringValue = theNote.filename
theTextView.string = theNote.noteText
theTextView.display()
print("theTextView.string set to "+theTextView.string!+" in NoteViewItem "+String(self))
}
else
{
theLabel.stringValue = "Empty note?"
}
}
}
// MARK: Functions
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
// Hopefully this will set the note's background to white.
view.wantsLayer = true
view.layer?.backgroundColor = NSColor.whiteColor().CGColor
}
// MARK: - NSTextViewDelegate
/*
override func controlTextDidChange(notification: NSNotification)
{
print("Control text changed.")
}
*/
func textDidChange(notification: NSNotification)
{
if let noteyMcNoteface = theNote
{
print("On edit, we have a note: "+String(noteyMcNoteface))
}
else
{
print("On edit, we have no note. I am NoteViewItem "+String(self))
}
}
}
I figured it out. My delegate, in the TextView, was connected to the wrong object in the Interface Builder for NoteViewItem.xib. I had connected it to the object labelled Note View Item, under objects in the outline. It should have been connected to File's Owner instead, since File's Owner stands for the NoteViewItem.swift class associated with the xib.
You'd think that if you want to connect the delegate to the NoteViewItem class and there is exactly one Note View Item listed in the outline, then that Note View Item is the thing you want to connect it to. Nope, you connect it to something entirely different that isn't called the Note View Item but is the Note View Item. I'm glad Interface Builder makes things so simple.