This question already has an answer here:
Swift Access Controll Example
(1 answer)
Closed 8 years ago.
i have this Class in my ViewController.swift for example ...
class Person {
internal let name: String
init(name: String) {
self.name = name
}
}
class ViewController: UIViewController {
}
and in my SecondViewController i have
override func viewDidLoad() {
super.viewDidLoad()
let person = Person(name: "")
println(person.name)
}
How can I assign a value a name from the internal of the view controller class ?
Just create an instance of it:
var person = Person(name: "Person Name")
I don't know what you are going to do with it - it can be either a local variable in a view controller method, or a view controller property.
You can use this to create an instance and it's name property
var personsName = Person(name: "persons name")
Related
This question already has answers here:
What is "self" used for in Swift?
(10 answers)
Closed 4 years ago.
How this part o code works ? Cand someone explain more about self ?
import MapKit
class Artwork: NSObject, MKAnnotation {
let title: String?
let locationName: String
let discipline: String
let coordinate: CLLocationCoordinate2D
init(title: String, locationName: String, discipline: String, coordinate: CLLocationCoordinate2D) {
self.title = title
self.locationName = locationName
self.discipline = discipline
self.coordinate = coordinate
super.init()
}
}
Self is used when accessing the class that you are writing the code in.
class Cat {
let catName = "My Cat"
func name() {
self.nameCat()
}
func nameCat() {
let catName = "Sam"
print(catName)
print(self.catName)
}
}
in this example when running name(), the terminal would print:
"Sam" and then "My Cat". A variable without the "self" would have the value of the most 'recent' reference of that variable while a variable with "self" will reference the class. This also works with functions. You can run self.nameCat() to access the "nameCat" function inside the Cat class. Basically, "self" returns the instance of the class you are writing code in.
I am working on a project containing a "Create New Account" view controller with its accompanying Swift class called "CreateNewAccount." The user can place 4 input values into this view controller, a first name, last name, user name, and password. Upon clicking the "Create Account" button in this VC, the 4 input values are passed on to a Swift class (within the model layer of MVC, I believe) called UserInfoRetrieveModel where they are supposedly stored.
I would then like to pass these values to another Swift class (that is a model as well) called UserInfoModel, which will then delegate out the first name value to the text value of label located in a VC called "ThanksForJoining" (and its accompanying class).
I have figured out how to pass values from VC to model (CreateNewAccount to UserInfoRetrieveModel) and from model to VC (UserInfoModel to ThanksForJoining), but somewhere in my transference from model to model (UserInfoRetrieveModel to UserInfoModel) the values initially inputted into "CreateNewAccount," which I would like to pass over to the second model class UserInfoModel become nil.
Below is the code for CreateNewAccount, UserInfoRetrieve, UserInfo, and ThanksForJoining:
CreateNewAccount ->
import UIKit
class CreateNewAccount: UIViewController{
#IBOutlet weak var FNInput: UITextField!
#IBOutlet weak var LNInput: UITextField!
#IBOutlet weak var usernameInput: UITextField!
#IBOutlet weak var passwordInput: UITextField!
var uInfoRetrieve = UInfoRetrieveModel()
#IBAction func thanksForJoining(_ sender: Any) {
uInfoRetrieve.firstName = FNInput.text!
uInfoRetrieve.lastName = LNInput.text!
uInfoRetrieve.userName = usernameInput.text!
uInfoRetrieve.password = passwordInput.text!
uInfoRetrieve.delegate = self
uInfoRetrieve.retrieving()
}
override func viewDidLoad() {
super.viewDidLoad()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
extension CreateNewAccount: UInfoRetrieveModelDelegate{
func credentialTransfer(data: String) {
print(data)
}
}
UserInfoRetrieve ->
import Foundation
protocol UInfoRetrieveModelDelegate: class {
func credentialTransfer(data:String)
}
class UInfoRetrieveModel: NSObject {
weak var delegate: UInfoRetrieveModelDelegate?
var firstName: String = ""
var lastName: String = ""
var userName: String = ""
var password: String = ""
func retrieving(){
delegate?.credentialTransfer(data: firstName)
delegate?.credentialTransfer(data: lastName)
delegate?.credentialTransfer(data: userName)
delegate?.credentialTransfer(data: password)
}
}
UserInfo ->
import Foundation
protocol UserInfoModelDelegate: class {
func didReceiveDataUpdate(data: String)
}
class UserInfoModel {
weak var delegate: UserInfoModelDelegate?
let uInfoRetrieve = UInfoRetrieveModel()
func requestData() -> Array<String> {
let firstName = uInfoRetrieve.firstName
let lastName = uInfoRetrieve.lastName
let userName = uInfoRetrieve.userName
let password = uInfoRetrieve.password
delegate?.didReceiveDataUpdate(data: firstName)
delegate?.didReceiveDataUpdate(data: lastName)
delegate?.didReceiveDataUpdate(data: userName)
delegate?.didReceiveDataUpdate(data: password)
let credentials = [firstName, lastName, userName, password] as [Any]
return credentials as! Array<String>
}
}
ThanksForJoining ->
import UIKit
class ThanksForJoining: UIViewController {
var userInfo = UserInfoModel()
#IBOutlet weak var firstName: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
userInfo.delegate = self
firstName.text = userInfo.requestData()[0]
print("yo")
print(userInfo.requestData()[0])
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
extension ThanksForJoining: UserInfoModelDelegate {
func didReceiveDataUpdate(data: String) {
print(data)
}
}
UserInfoModel and CreateNewAccount do both create a new instance of UInfoRetrieveModel. You have to connect them properly for them to pass on information.
Connecting properly means (in the simplest form) one constructs the other and sets itself as the delegate of the other, so UInfoRetrieveModel can pass on data. The constructing of a child model is usually done via a computed property.
Example
struct Account {
let firstName: String, lastName: String
let userName: String, password: String
}
extension UInfoRetrieveModelDelegate: class {
createAccount(_ account: Account): Bool
}
extension UserInfoModel: UInfoRetrieveModelDelegate{
func createAccount(_ account: Account) -> Bool {
// Handling creation of account.
return success == true
}
var newUInfoRetrieveModel: UInfoRetrieveModel {
let helperModel = UInfoRetrieveModel(parent: self)
helperModel.delegate = self
return helperModel
}
}
Explanation
Yes. You usually have a Model, your data, then have something that controls access to it to make changes on your model, manages how the model is stored, maybe syncing with a cloud-service, thats the ModelController which you pass around between ViewControllers, more/other controllers you usually use incase that makes things simpler. In your case you would probably pass createAccount(the call) on to a controller/viewController which is in charge of telling the modelController to create the account and then telling one of its views/viewControllers to display the modal/whatever.
The usual way to pass data to a higher level is to have for the viewController/controller a delegate it uses to communicate with higher up, the one “responsible for actions the ViewController/controller cannot do by itself”, eg pushing data up(creation calls, modification calls, deletion calls) if it makes no sense to give it a modelController since its not control of that part of the application, etc. In your case you can of course pass a modelController to each little viewController/view, but its usually more practical/simpler to only give it to the one controlling the part and let others communicate with that currently-that-part-controlling controller/viewController.
More partical here means that you may not want CreateAccountViewController to display the success dialog, but rather another, which CreateAccountViewController can then do not by itself since it’s not on the stack anymore.
I'm trying (unsuccessfully) to build a TreeController-controlled NSOutlineView. I've gone through a bunch of tutorials, but they all pre-load the data before starting anything, and this won't work for me.
I have a simple class for a device:
import Cocoa
class Device: NSObject {
let name : String
var children = [Service]()
var serviceNo = 1
var count = 0
init(name: String){
self.name = name
}
func addService(serviceName: String){
let serv = "\(serviceName) # \(serviceNo)"
children.append(Service(name: serv))
serviceNo += 1
count = children.count
}
func isLeaf() -> Bool {
return children.count < 1
}
}
I also have an even more simple class for the 'Service':
import Cocoa
class Service: NSObject {
let name: String
init(name: String){
self.name = name
}
}
Finally, I have the ViewController:
class ViewController: NSViewController {
var stepper = 0
dynamic var devices = [Device]()
override func viewDidLoad() {
super.viewDidLoad()
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
#IBAction func addDeviceAction(_ sender: Any) {
let str = "New Device #\(stepper)"
devices.append(Device(name: str))
stepper += 1
print("Added Device: \(devices[devices.count-1].name)")
}
#IBAction func addService(_ sender: Any) {
for i in 0..<devices.count {
devices[i].addService(serviceName: "New Service")
}
}
}
Obviously I have 2 buttons, one that adds a 'device' and one that adds a 'service' to each device.
What I can't make happen is any of this data show up in the NSOutlineView. I've set the TreeController's Object Controller Property to Mode: Class and Class: Device, and without setting the Children, Count, or Leaf properties I get (predictably):
2017-01-04 17:20:19.337129 OutlineTest[12550:1536405] Warning: [object class: Device] childrenKeyPath cannot be nil. To eliminate this log message, set the childrenKeyPath attribute in Interface Builder
If I then set the Children property to 'children' things go very bad:
2017-01-04 17:23:11.150627 OutlineTest[12695:1548039] [General] [ addObserver:forKeyPath:options:context:] is not supported. Key path: children
All I'm trying to do is set up the NSOutlineView to take input from the NSTreeController so that when a new 'Device' is added to the devices[] array, it shows up in the Outline View.
If anyone could point me in the right direction here I'd be most grateful.
Much gratitude to Warren for the hugely helpful work. I've got it (mostly) working. A couple of things that I also needed to do, in addition to Warren's suggestions:
Set the datastore for the Tree Controller
Bind the OutlineView to the TreeController
Bind the Column to the TreeController
Bind the TableView Cell to the Table Cell View (yes, really)
Once all that was done, I had to play around with the actual datastore a bit:
var name = "Bluetooth Devices Root"
var deviceStore = [Device]()
#IBOutlet var treeController: NSTreeController!
#IBOutlet weak var outlineView: NSOutlineView!
override func viewDidLoad() {
super.viewDidLoad()
deviceStore.append(Device(name: "Bluetooth Devices"))
self.treeController.content = self
}
override var representedObject: Any? {
didSet {
// Update the view, if already loaded.
}
}
#IBAction func addDeviceAction(_ sender: Any) {
if(deviceStore[0].name == "Bluetooth Devices"){
deviceStore.remove(at: 0)
}
Turns out the Root cannot be child-less at the beginning, at least as far as I can tell. Once I add a child, I can delete the place-holder value and the tree seems to work (mostly) as I want. One other thing is that I have to reload the data and redisplay the outline whenever the data changes:
outlineView.reloadData()
outlineView.setNeedsDisplay()
Without that, nothing. I still don't have the data updating correctly (see comments below Warren's answer) but I'm almost there.
To state the obvious, a NSTreeController manages a tree of objects all of which need to answer the following three questions/requests.
Are you a leaf i.e do you have no children? = leafKeyPath
If you are not a leaf, how many children do you have ? = countKeyPath
Give me your children! = childrenKeyPath
Its simple to set these up in IB or programatically. A fairly standard set of properties is respectively.
isLeaf
childCount
children
But its totally arbitrary and can be any set of properties that answer those questions.
I normally set up a protocol named something like TreeNode and make all my objects conform to it.
#objc protocol TreeNode:class {
var isLeaf:Bool { get }
var childCount:Int { get }
var children:[TreeNode] { get }
}
For your Device object you answer 2 out 3 question with isLeaf and children but don't answer the childCount question.
Your Device's children are Service objects and they answer none of that which is some of the reason why you are getting the exceptions.
So to fix up your code a possible solution is ...
The Service object
class Service: NSObject, TreeNode {
let name: String
init(name: String){
self.name = name
}
var isLeaf:Bool {
return true
}
var childCount:Int {
return 0
}
var children:[TreeNode] {
return []
}
}
The Device object
class Device: NSObject, TreeNode {
let name : String
var serviceStore = [Service]()
init(name: String){
self.name = name
}
var isLeaf:Bool {
return serviceStore.isEmpty
}
var childCount:Int {
return serviceStore.count
}
var children:[TreeNode] {
return serviceStore
}
}
And a horrible thing to do from a MVC perspective but convenient for this answer. The root object.
class ViewController: NSViewController, TreeNode {
var deviceStore = [Device]()
var name = "Henry" //whatever you want to name your root
var isLeaf:Bool {
return deviceStore.isEmpty
}
var childCount:Int {
return deviceStore.count
}
var children:[TreeNode] {
return deviceStore
}
}
So all you need to do is set the content of your treeController. Lets assume you have an IBOutlet to it in your ViewController.
class ViewController: NSViewController, TreeNode {
#IBOutlet var treeController:NSTreeController!
#IBOutlet var outlineView:NSOutlineView!
override func viewDidLoad() {
super.viewDidLoad()
treeController.content = self
}
Now each time you append a Device or add a Service just call reloadItem on the outlineView (that you also need an outlet to)
#IBAction func addDeviceAction(_ sender: Any) {
let str = "New Device #\(stepper)"
devices.append(Device(name: str))
stepper += 1
print("Added Device: \(devices[devices.count-1].name)")
outlineView.reloadItem(self, reloadChildren: true)
}
Thats the basics and should get you started but the docs for NSOutlineView & NSTreeController have a lot more info.
EDIT
In addition to the stuff above you need to bind your outline view to your tree controller.
First ensure your Outline View is in view mode.
Next bind the table column to arrangedObjects on the tree controller.
Last bind the text cell to the relevant key path. In your case it's name. objectValue is the reference to your object in the cell.
I'm pretty new to Swift. I'm creating an application that allows a user to create registration forms. I have two files/scenes, FirstViewController, and SecondViewController. The SecondViewController allows the user to create a question. The FirstViewController will display all the created questions in a UITableView. In my SecondViewController I have a class called Question which basically helps me create a question, it is shown below for context.
class Question {
var Label: String
var required: Int
// create question
init (Label: String, required: Int) {
self.Label = Label
self.required = required
}
}
class textInput: Question {
var placeHolder: String
init (placeHolder: String, Label: String, required: Int) {
self.placeHolder = placeHolder
super.init(Label: Label, required: required)
}
}
class multiChoice: Question {
var answers: [String]
init(answers: [String], Label: String, required: Int) {
self.answers = answers
super.init(Label: Label, required: required)
}
}
In the FirstViewController I need to create an array of that type to keep a running list of all the questions in the UITableView...
var formQuestions: [Question]
Obviously the FirstViewController does not have access to this custom object type. My question is how do I make it so that it does? I could copy and paste the entire class over to my FirstViewController but that would be terrible programming...
Thanks for the help.
Your FirstViewController doesn't have access to the Question class and its subclasses because they are all declared in SecondViewController. This means they are local to SecondViewController and nowhere else can access it. What you need to do is to make the question class global.
So at the moment your classes are like: (contents omitted)
class SecondViewController: UIViewController {
class Question {
}
class TextInputQuestion: Question {
}
class MultiChoiceQuestion: Question {
}
}
You should move them out of the SecondViewController:
class SecondViewController {
}
class Question {
}
class TextInputQuestion: Question {
}
class MultiChoiceQuestion: Question {
}
Oh by the way, I renamed your class names! You should always use PascalCase for classes and I think adding the word Question would be more descriptive of what they are.
Let's say I have
struct cat {
var paws: int
var name: string
var breed: string
}
How would i go about segueing an instance to a new destination controller? Particularly, this instance from an array to a new DC?
prepare for segue
{
if segue.identifier == "segue"
var nextVC = segue.desitnationviewcontroller as ...
nextvc.instance = ?
}
You can just assign it like this:
let someCat = cat(paws: 4, name: "Kitty", breed: "Unknown")
let arrayCat = [cat(paws: 5, name: "Mutant", breed: "Unknown"),
cat(paws: 4, name: "John", breed: "Doe")]
var nextVC = segue.desitnationviewcontroller as SomeViewController
nextVC.somePropertyName = someCat // or arrayCat if you're using an array
In your SomeViewController, you'll have to have a property with type cat and you can just assign it. For example:
class SomeViewController: UIViewController {
var somePropertyName: cat? // [cat]() if it's an array of type cat
}
Also, for your convenience I added a link to Apple's documentation of Swift. The link is here.