I am trying to pass data from my model in my file, CalculatorBrain, to a ViewController through a segue. The var that I am trying to pass is designated as a PropertyList as shown below:
var program: PropertyList { // guaranteed to be PropertyList
get {
return opStack.map { $0.description }
}
set {
if let opSymbols = newValue as? Array<String> {
var newOpStack = [Op]()
for opSymbol in opSymbols {
if let op = knownOps[opSymbol] {
newOpStack.append(op)
} else if let operand = NSNumberFormatter().numberFromString(opSymbol)?.doubleValue {
newOpStack.append(.Operand(operand))
}
}
opStack = newOpStack
}
}
}
This is a multiple MVC project, and the override segue function is in a ViewController called "CalculatorViewController." The function tries to pass the data from the model to the ViewController known as "GraphingViewController" like this:
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
var destination: UIViewController? = segue.destinationViewController
if let navCon = destination as? UINavigationController {
destination = navCon.visibleViewController
}
if let gvc = destination as? GraphingViewController {
gvc.program = brain.program
}
}
I set-up the variable program in my GraphingViewController as follows:
var program: AnyObject?
When I press the button that calls the segue, it does fire. What happens is that the data in brain.program gets copied into gvc.program. However, it is then LOST to the model. I don't know why this happens. When I print the program out from the controller in the segue, I do see the program as it should be shown. However, when I print it anywhere after the segue, it has disappeared.
Why would data, after the override segue function is called, be removed?
EDIT: This is the delegate function in the GraphingViewController. When I print out brain.program from here, it doesn't print out the full opStack.
func graphForGraphView(xAxisValue: CGFloat, sender: GraphView) -> CGPoint? {
print("BRAIN PROGRAM 2: \(brain.program)")
brain.variableValues[brain.variableM] = 40.0
if let yValue = brain.returnEvaluate() {
print(yValue)
print("The returned value is: \(yValue)")
let point = CGPoint(x: 40.0, y: CGFloat(yValue))
if !point.x.isNormal || !point.y.isNormal {
return nil
} else {
return point
}
}
return nil
}
Related
I wanted to create a pop up for one of my UIViewController and found this repo on GitHub.
It is working fine with my InfoViewController which only has 4 UILabels (I think this might be the problem that it is not showing up when you use reusable cells)
But somehow it is not working with my StructureNavigationListViewController and I do not know why.
I call the didTapCategory method in my MainViewController where the StructureNavigationController should pop up but I only see the dimming view (which is weird cause the tap recognizer and pan gestures are working fine but no content is showing up)
In my MainViewController I set up the popup like before:
#IBAction func didTapCategory(_ sender: UIBarButtonItem) {
let popupContent = StructureNavigationListViewController.create()
let cardpopUp = SBCardPopupViewController(contentViewController: popupContent)
cardpopUp.show(onViewController: self)
}
In my StructureNavigationListViewController I set up the table view and the pop up:
public var popupViewController: SBCardPopupViewController?
public var allowsTapToDismissPopupCard: Bool = true
public var allowsSwipeToDismissPopupCard: Bool = true
static func create() -> UIViewController {
let sb = UIStoryboard(name: "Main", bundle: nil)
let vc = sb.instantiateViewController(withIdentifier: "StructureNavigationListViewController") as! StructureNavigationListViewController
return vc
}
#IBOutlet var tableView: UITableView!
var structures = Variable<[Structure]>([])
public var treeSource: StructureTreeSource?
let disposeBag = DisposeBag()
var depthDictionary : [String : Int] = [:]
public override func viewDidLoad() {
structures.asObservable()
.bind(to:tableView.rx.items) {(tableView, row, structure) in
let cell = tableView.dequeueReusableCell(withIdentifier: "StructureNavigationCell", for: IndexPath(row: row, section: 0)) as! StructureNavigationCell
cell.structureLabel.text = structure.name
cell.spacingViewWidthConstraint.constant = 20 * CGFloat(self.depthDictionary[structure.id]!)
return cell
}.disposed(by:disposeBag)
_ = tableView.rx.modelSelected(Structure.self).subscribe(onNext: { structure in
let storyBoard = UIStoryboard(name:"Main", bundle:nil)
let plansViewCtrl = storyBoard.instantiateViewController(withIdentifier: "PlansViewController2") as! PlansViewController2
self.treeSource?.select(structure)
plansViewCtrl.treeSource = self.treeSource
plansViewCtrl.navigationItem.title = structure.name
self.show(plansViewCtrl, sender: self)
if let mainVC = self.parent as? ProjectOverViewTabController2 {
mainVC.addChildView(viewController: plansViewCtrl, in: mainVC.scrollView)
}
})
showList()
}
func showList() {
if treeSource == nil {
treeSource = StructureTreeSource(projectId:GlobalState.selectedProjectId!)
}
//The following piece of code achieves the correct order of structures and their substructures.
//It is extremely bad designed and rather expensive with lots of structures and should
//therefore be refactored!
if let strctrs = getStructures() {
var sortedStructures : [Structure] = []
while(sortedStructures.count != strctrs.count) {
for strct in strctrs {
if let _ = sortedStructures.index(of: strct) {
continue
} else {
depthDictionary[strct.id] = getDepthOfNode(structure: strct, depth: 1)
if let structures = getStructures() {
if let parent = structures.first(where: {$0.id == strct.parentId}) {
if let index = sortedStructures.index(of: parent) {
sortedStructures.insert(strct, at: index+1)
}
} else {
sortedStructures.insert(strct, at: 0)
}
}
}
}
}
structures.value = sortedStructures
tableView.reloadData()
}
}
func getDepthOfNode(structure: Structure, depth: Int) -> Int {
if(structure.parentId == nil || structure.parentId == "") {
return depth
} else {
if let structures = getStructures() {
if let parent = structures.first(where: {$0.id == structure.parentId}) {
return getDepthOfNode(structure: parent, depth: depth + 1)
}
}
}
return -1
}
private func getStructures() -> Results<Structure>? {
do {
if let projectId = GlobalState.selectedProjectId {
return try Structure.db.by(projectId: projectId)
}
} catch { Log.db.error(error: error) }
return nil
}
}
Lot of code here. Sorry..
Is it because I call the create() method after the viewDidLoad() dequeues the cells?
It's hard to tell what is the problem, since you left no information about where didTapCategory is supposed to be called, but maybe it has something to do with your modelSelected subscription being prematurely released?
Edit:
As posted here: https://stackoverflow.com/a/28896452/11851832 if your custom cell is built with Interface Builder then you should register the Nib, not the class:
tableView.registerNib(UINib(nibName: "CustomCell", bundle: nil), forCellReuseIdentifier: "CustomCellIdentifier")
I have two view controllers. VC1 & VC2. VC1 is passing a variable which keeps changing & updating every second on VC1, in my case, it is the nearest beacon which is handled by a method in VC1.
VC1 code:
var id: Int = 0 // initializing
// send data to VC2
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let vc2 = segue.destination as? navigationScreenVC else { return }
vc2.id2 = id
}
VC2 code:
var id2: Int = 0
override func viewDidLoad() {
super.viewDidLoad()
print(VC2)
}
It is working where it sends the first value it encounters, but not when the value keeps changing, so I want that to be sent as soon as it triggers a change.
I tried to do didSet{} but it doesn't work that way.
Use a delegate pattern.
In VC2:
protocol VC2Delegate: AnyObject {
var id2: Int { get }
}
class VC2 {
weak var delegate: VC2Delegate?
override func viewDidLoad() {
super.viewDidLoad()
print(delegate?.id2)
}
}
In VC1:
class VC1: UIViewController, VC2Delegate {
...
var id2: Int = 0
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let vc2 = segue.destination as? navigationScreenVC else { return }
vc2.delegate = self
}
...
}
A ViewController should not be managing stuff after it stopped being visible. You should managing this in a separate class and waiting for updates from a delegate, lets say:
protocol BeaconUpdateListener : AnyObject {
func currentBeaconIdWasUpdated(to newValue: Int)
}
class BeaconManager {
struct DelegateWrapper {
weak var delegate : BeaconUpdateListener?
}
static let delegates = [DelegateWrapper]()
static var currentId : Int = -1 {
didSet {
delegates.forEach { (delegate) in
delegate.delegate?.currentBeaconIdWasUpdated(to: currentId)
}
}
}
}
Sample code, missing details. You could make your own or update this one. Now, having that data outside your UI code makes it easier to use from anywhere else, and update that code in the future. This way, you "subscribe" to id updates like this:
BeaconManager.delegates.append(OBJECT_THAT_NEEDS_TO_BE_NOTIFIED)
... update your id like this:
BeaconManager.currentId = 65421687543152
... and wait for updates like this:
class VC2 : ViewController, BeaconUpdateListener {
func currentBeaconIdWasUpdated(to newValue: Int) {
// Do stuff once i receive the update
}
// ...
}
I am trying to pass data receive from a network call to another view controller when user has clicked on a button. When making printing on the FirstVC, data is in, but when printing the result in the SecondVC, there is no more value. I don' t want to use delegate but closure instead.
Also, when trying to retain the memory cycle, an error appear...
class APIsRuler {
static var oneRecipeFound: ((OneRecipeSearch) -> ())?
}
class FirstVC: UIViewController {
func cellIsClicked(index: Int) {
APIsRuler.shared.getRecipe(from: recipeID) { (success, oneRecipe) in
if success, let oneRecipe = oneRecipe {
APIsRuler.oneRecipeFound?(oneRecipe)
self.performSegue(withIdentifier: "goToSecondVC", sender: self)
}
}
}
}
Class SecondVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
APIsRuler.oneRecipeFound = { result in
print(result)
}
}
}
Doing this in SecondVC
APIsRuler.oneRecipeFound = { result in
print(result)
}
and this in first
APIsRuler.oneRecipeFound?(oneRecipe)
have no inner communications , you need to read your data directly from the shared class in the secondVc after the segue or send it in
self.performSegue(withIdentifier: "goToSecondVC", sender: <#Herererere#>)
and implement prepareForSegue
Let’s think about the order in which things are happening:
class APIsRuler {
static var oneRecipeFound: ((OneRecipeSearch) -> ())? // 1
}
class FirstVC: UIViewController {
func cellIsClicked(index: Int) {
APIsRuler.shared.getRecipe(from: recipeID) { (success, oneRecipe) in
if success, let oneRecipe = oneRecipe {
APIsRuler.oneRecipeFound?(oneRecipe) // 2
self.performSegue(withIdentifier: "goToSecondVC", sender: self)
}
}
}
}
Class SecondVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
APIsRuler.oneRecipeFound = { result in // 3
print(result)
}
}
}
oneRecipeFound starts out life empty: it is nil.
In FirstVC, the cell is clicked. We call oneRecipeFound. It is still nil, so nothing happens.
In SecondVC, we set the value of oneRecipeFound. Now it has a value, but the call has already happened.
So unless you have a time machine in your pocket, so that you can reverse that order of events somehow, the strategy you’ve outlined is doomed to failure. Of course, if you call oneRecipeFound after setting it, it will work. For example:
Class SecondVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
APIsRuler.oneRecipeFound = { result in
print(result)
}
APIsRuler.oneRecipeFound?(oneRecipe) // prints
}
}
I have two Core Data entities which populate a UITableView with 2 sections, one entity for each section. When the user taps on a table row, they are directed to another view where the data of that row is sent. It is currently implemented like this:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "editValue") {
let secondViewController = segue.destination as! EditValuesViewController
if send_array_inc.isEmpty {
secondViewController.send_array_exp = send_array_exp
} else if send_array_exp.isEmpty {
secondViewController.send_array_inc = send_array_inc
}
}
}
The Question:
Since there are two entities, there are two possible types (Income and Expenses) for the data being sent into the next view. How can I use that data in the next view with one variable? I am doing the below in ViewDidLoad but the scope of send_array remains within that function. How can I make send_array available outside?
if send_array_inc.isEmpty {
var send_array = [Expenses]()
send_array = send_array_exp
} else if send_array_exp.isEmpty {
var send_array = [Income]()
send_array = send_array_inc
}
I ideally want to do this without creating a separate view for each entity result but I am open to refactor if another solution would be better and realistic. Thank you
Make your two types of data objects conform to a shared protocol. Make the destination view controller's send_array be an object conforming to that protocol.
In your EditValuesViewController's code, interrogate the send_array to figure out which type of data object was passed in.
Edit:
Define a protocol
#protocol dataArrayProtocol {
var dataArray: Array
}
Define 2 structs that conform to that protocol
struct ExpensesArrayStruct: dataArrayProtocol {
var dataArray: [Expenses]
}
struct IncomeArrayStruct: dataArrayProtocol {
var dataArray: [Income]
}
give your EditValuesViewController a property that conforms to that protocol
class EditValuesViewController: UIViewController {
var dataArrayStruct: dataArrayProtocol
}
And your prepare(for:sender) method
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if (segue.identifier == "editValue") {
let secondViewController = segue.destination as! EditValuesViewController
if send_array_inc.isEmpty {
secondViewController.dataArrayStruct = ExpensesArrayStruct(dataArray: send_array_exp)
} else if send_array_exp.isEmpty {
secondViewController.dataArrayStruct = IncomeArrayStruct(dataArray: send_array_inc)
}
}
}
And to handle the data:
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if let expensesStruct = dataArrayStruct as? ExpensesArrayStruct {
//deal with expenses array
} else if let incomeStruct = dataArrayStruct as? IncomeArrayStruct {
//deal with income array
}
}
Note that I banged this code out in the SO editor and have not tried to compile it. I may have made some minor errors. It should give you the idea though.
Working in Swift3; I've got a pretty expensive operation running in a loop iterating through stuff and building it into an array that on return would be used as the content for an NSTableView.
I wanted a modal sheet showing progress for this so people don't think the app is frozen. By googling, looking around in here and not a small amount of trial and error I've managed to implement my progressbar and have it show progress adequately as the loop progresses.
The problem right now? Even though the sheet (implemented as an NSAlert, the progress bar is in the accesory view) works exactly as expected, the whole thing returns before the loop is finished.
Here's the code, hoping somebody can tell me what am I doing wrong:
class ProgressBar: NSAlert {
var progressBar = NSProgressIndicator()
var totalItems: Double = 0
var countItems: Double = 0
override init() {
progressBar.isIndeterminate = false
progressBar.style = .barStyle
super.init()
self.messageText = ""
self.informativeText = "Loading..."
self.accessoryView = NSView(frame: NSRect(x:0, y:0, width: 290, height: 16))
self.accessoryView?.addSubview(progressBar)
self.layout()
self.accessoryView?.setFrameOrigin(NSPoint(x:(self.accessoryView?.frame)!.minX,y:self.window.frame.maxY))
self.addButton(withTitle: "")
progressBar.sizeToFit()
progressBar.setFrameSize(NSSize(width:290, height: 16))
progressBar.usesThreadedAnimation = true
self.beginSheetModal(for: ControllersRef.sharedInstance.thePrefPane!.mainCustomView.window!, completionHandler: nil)
}
}
static var allUTIs: [SWDAContentItem] = {
var wrappedUtis: [SWDAContentItem] = []
let utis = LSWrappers.UTType.copyAllUTIs()
let a = ProgressBar()
a.totalItems = Double(utis.keys.count)
a.progressBar.maxValue = a.totalItems
DispatchQueue.global(qos: .default).async {
for uti in Array(utis.keys) {
a.countItems += 1.0
wrappedUtis.append(SWDAContentItem(type:SWDAContentType(rawValue: "UTI")!, uti))
Thread.sleep(forTimeInterval:0.0001)
DispatchQueue.main.async {
a.progressBar.doubleValue = a.countItems
if (a.countItems >= a.totalItems && a.totalItems != 0) {
ControllersRef.sharedInstance.thePrefPane!.mainCustomView.window?.endSheet(a.window)
}
}
}
}
Swift.print("We'll return now...")
return wrappedUtis // This returns before the loop is finished.
}()
In short, you're returning wrappedUtis before the asynchronous code has had a chance to finish. You cannot have the initialization closure return a value if the update process itself is happening asynchronously.
You clearly successfully diagnosed a performance problem in the initialization of allUTIs, and while doing this asynchronously is prudent, you shouldn't be doing that in that initialization block of the allUTIs property. Move this code that initiates the update of allUTIs into a separate function.
Looking at ProgressBar, it's really an alert, so I'd call it ProgressAlert to make that clear, but expose the necessary methods to update the NSProgressIndicator within that alert:
class ProgressAlert: NSAlert {
private let progressBar = NSProgressIndicator()
override init() {
super.init()
messageText = ""
informativeText = "Loading..."
accessoryView = NSView(frame: NSRect(x:0, y:0, width: 290, height: 16))
accessoryView?.addSubview(progressBar)
self.layout()
accessoryView?.setFrameOrigin(NSPoint(x:(self.accessoryView?.frame)!.minX,y:self.window.frame.maxY))
addButton(withTitle: "")
progressBar.isIndeterminate = false
progressBar.style = .barStyle
progressBar.sizeToFit()
progressBar.setFrameSize(NSSize(width:290, height: 16))
progressBar.usesThreadedAnimation = true
}
/// Increment progress bar in this alert.
func increment(by value: Double) {
progressBar.increment(by: value)
}
/// Set/get `maxValue` for the progress bar in this alert
var maxValue: Double {
get {
return progressBar.maxValue
}
set {
progressBar.maxValue = newValue
}
}
}
Note, this doesn't present the UI. That's the job of whomever presented it.
Then, rather than initiating this asynchronous population in the initialization closure (because initialization should always be synchronous), create a separate routine to populate it:
var allUTIs: [SWDAContentItem]?
private func populateAllUTIs(in window: NSWindow, completionHandler: #escaping () -> Void) {
let progressAlert = ProgressAlert()
progressAlert.beginSheetModal(for: window, completionHandler: nil)
var wrappedUtis = [SWDAContentItem]()
let utis = LSWrappers.UTType.copyAllUTIs()
progressAlert.maxValue = Double(utis.keys.count)
DispatchQueue.global(qos: .default).async {
for uti in Array(utis.keys) {
wrappedUtis.append(SWDAContentItem(type:SWDAContentType(rawValue: "UTI")!, uti))
DispatchQueue.main.async { [weak progressAlert] in
progressAlert?.increment(by: 1)
}
}
DispatchQueue.main.async { [weak self, weak window] in
self?.allUTIs = wrappedUtis
window?.endSheet(progressAlert.window)
completionHandler()
}
}
}
Now, you declared allUTIs to be static, so you can tweak the above to do that, too, but it seems like it's more appropriate to make it an instance variable.
Anyway, you can then populate that array with something like:
populateAllUTIs(in: view.window!) {
// do something
print("done")
}
Below, you said:
In practice, this means allUTIs is only actually initiated when the appropriate TabViewItem is selected for the first time (which is why I initialize it with a closure like that). So, I'm not really sure how to refactor this, or where should I move the actual initialization. Please keep in mind that I'm pretty much a newbie; this is my first Swift (also Cocoa) project, and I've been learning both for a couple of weeks.
If you want to instantiate this when the tab is selected, then hook into the child view controllers viewDidLoad. Or you can do it in the tab view controller's tabView(_:didSelect:)
But if the population of allUTIs is so slow, are you sure you want to do this lazily? Why not trigger this instantiation sooner, so that there's less likely to be a delay when the user selects that tab. In that case, you might trigger it the tab view controller's own viewDidLoad, so that the tab that needs those UTIs is more likely to have them.
So, if I were considering a more radical redesign, I might first change my model object to further isolate its update process from any specific UI, but rather to simply return (and update) a Progress object.
class Model {
var allUTIs: [SWDAContentItem]?
func startUTIRetrieval(completionHandler: (() -> Void)? = nil) -> Progress {
var wrappedUtis = [SWDAContentItem]()
let utis = LSWrappers.UTType.copyAllUTIs()
let progress = Progress(totalUnitCount: Int64(utis.keys.count))
DispatchQueue.global(qos: .default).async {
for uti in Array(utis.keys) {
wrappedUtis.append(SWDAContentItem(type:SWDAContentType(rawValue: "UTI")!, uti))
DispatchQueue.main.async {
progress.completedUnitCount += 1
}
}
DispatchQueue.main.async { [weak self] in
self?.allUTIs = wrappedUtis
completionHandler?()
}
}
return progress
}
}
Then, I might have the tab bar controller instantiate this and share the progress with whatever view controller needed it:
class TabViewController: NSTabViewController {
var model: Model!
var progress: Progress?
override func viewDidLoad() {
super.viewDidLoad()
model = Model()
progress = model.startUTIRetrieval()
tabView.delegate = self
}
override func tabView(_ tabView: NSTabView, didSelect tabViewItem: NSTabViewItem?) {
super.tabView(tabView, didSelect: tabViewItem)
if let item = tabViewItem, let controller = childViewControllers[tabView.indexOfTabViewItem(item)] as? ViewController {
controller.progress = progress
}
}
}
Then the view controller could observe this Progress object, to figure out whether it needs to update its UI to reflect this:
class ViewController: NSViewController {
weak var progress: Progress? { didSet { startObserving() } }
weak var progressAlert: ProgressAlert?
private var observerContext = 0
private func startObserving() {
guard let progress = progress, progress.completedUnitCount < progress.totalUnitCount else { return }
let alert = ProgressAlert()
alert.beginSheetModal(for: view.window!)
progressAlert = alert
progress.addObserver(self, forKeyPath: "fractionCompleted", context: &observerContext)
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
guard let progress = object as? Progress, context == &observerContext else {
super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
return
}
dispatchPrecondition(condition: .onQueue(.main))
if progress.completedUnitCount < progress.totalUnitCount {
progressAlert?.doubleValue = progress.fractionCompleted * 100
} else {
progress.removeObserver(self, forKeyPath: "fractionCompleted")
view.window?.endSheet(progressAlert!.window)
}
}
deinit {
progress?.removeObserver(self, forKeyPath: "fractionCompleted")
}
}
And, in this case, the ProgressAlert only would worry about doubleValue:
class ProgressAlert: NSAlert {
private let progressBar = NSProgressIndicator()
override init() {
super.init()
messageText = ""
informativeText = "Loading..."
accessoryView = NSView(frame: NSRect(x:0, y:0, width: 290, height: 16))
accessoryView?.addSubview(progressBar)
self.layout()
accessoryView?.setFrameOrigin(NSPoint(x:(self.accessoryView?.frame)!.minX,y:self.window.frame.maxY))
addButton(withTitle: "")
progressBar.isIndeterminate = false
progressBar.style = .barStyle
progressBar.sizeToFit()
progressBar.setFrameSize(NSSize(width: 290, height: 16))
progressBar.usesThreadedAnimation = true
}
/// Set/get `maxValue` for the progress bar in this alert
var doubleValue: Double {
get {
return progressBar.doubleValue
}
set {
progressBar.doubleValue = newValue
}
}
}
I must note, though, that if these UTIs are only needed for that one tab, it raises the question as to whether you should be using a NSAlert based UI at all. The alert blocks the whole window, and you may want to block interaction with only that one tab.