I am trying to send multiple objects from my initial view controller to my Username VC. Here is the segue code from my controllers: The issue comes when I add in the code to send the second object, termreport. If I delete the termsM and the assignment, it send the students as usually, but I also need to send the termReport object. How would I fix this?
ViewControler:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let students = sender as AnyObject as? [Student]
else { return }
guard let termsM = sender as AnyObject as? [TermReport] //How would I send both objects?
else { return }
if let secondVC = segue.destination as? UsernameVC {
secondVC.students = students
secondVC.userWebView = webView
secondVC.terms = termsM // not sending
}
let gradeResponse = try Parser(innerHTML)
self.performSegue(withIdentifier: "ShowStudents", sender: gradeResponse.students)
self.performSegue(withIdentifier: "ShowStudents", sender: gradeResponse.termReports) //how would I send both variables?
UsernameVC:
var terms: [TermReport]!
override func viewDidLoad() {
print("TERM \(terms[0].grades[3])")//returns found nil optional ERROR
}
You have to include all of the variables you want to send to another ViewController using a segue into a single object (which can be a collection as well). You either create a custom class/struct that has properties with type [Student] and [TermReport] or put these into a native collection (Tuple or Dictionary).
Create custom struct:
struct TermData {
var students = [Student]()
var termReports = [TermReport]()
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard let segueData = sender as? TermData
else { return }
if let secondVC = segue.destination as? UsernameVC {
secondVC.students = segueData.students
secondVC.userWebView = webView
secondVC.terms = segueData.termReports
}
}
let gradeResponse = try Parser(innerHTML)
let termData = TermData(students: gradeResponse.students, termReports: gradeResponse.termReports)
self.performSegue(withIdentifier: "ShowStudents", sender: termData)
Related
I'm preparing for a Segue (just learning at the moment!) and want to pass an array, which is created in a function, through a segue to arrive at the new view controller.
It's working fine if I just put a text string in there, but when I try change to an array it is blank - I think because it can't access the array because it's outside the scope - but I'm stuck on how to do it
Here's the initial VC code :
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController {
destVC.workoutName = (testArray)
}
}
//Get the new view controller using segue.destinationViewController.
//Pass the selected object to the new view controller.
}
func testfunction() {
let testArray = ["blah","blah","ploop"]
}
and the 'receiving VC code'
class WorkoutViewController: UIViewController {
var workoutName = [String]()
override func viewDidLoad() {
super.viewDidLoad()
print(workoutName)
// Do any additional setup after loading the view.
}
I'm nearly there with it but think I must be missing something basic. How do you do this passing arrays/other variables created in functions?
If the function had more than 1 variable/array, would that change the approach? I.e. one function might produce the exercises in the workout AND the number of reps for example
You can send it in sender
self.performSegue(withIdentifier: "goToWorkout ", sender: testArray)
and in
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController {
destVC.workoutName = sender as! [String]
}
}
Yes, both occurrences of testArray are not in the same scope and the compiler complains.
Declare the function this way
func testfunction() -> [String] {
let testArray = ["blah","blah","ploop"]
return testArray
}
and assign the array by calling the function
destVC.workoutName = testfunction()
Your issue is caused by testArray being a local variable defined inside the testfunction function making it only accessible from inside the function. If you want to make a variable accessible from everywhere inside the class, you'll have to make it an instance property.
class InitialVC: UIViewController {
let testArray = ["blah","blah","ploop"]
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController {
destVC.workoutName = testArray
}
}
//Get the new view controller using segue.destinationViewController.
//Pass the selected object to the new view controller.
}
}
When saying:
destVC.workoutName = (testArray)
in the prepare(for segue: UIStoryboardSegue, sender: Any?) method, it definitely doesn't refers to testArray variable in testfunction(), since it is a local variable. If you are not getting a compile time error at the above line, then probably your declaring testArray somewhere in the view controller or maybe globally in the app.
So what you could do is to declare testfunction() as testfunction() -> [String]:
func testfunction() -> [String] {
return["blah","blah","ploop"]
}
thus:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController {
destVC.workoutName = testfunction()
}
}
}
func testfunction() -> [String] {
return ["blah","blah","ploop"]
}
I guess this is what you want. Functions / methods can return values. It can be achieved by the -> syntax.
Now you can use like:
destVC.workoutName = testfunction()
Few notes
Functions, methods and variables should be named through camel case notation. So, instead of testfunction you should write testFunction (maybe choose a better name also).
Do not forget to read Apple documentation on the subject: Functions.
I'm nearly there with a small basic program I'm writing (still learning) and I've hit a roadblock.
I can now pass 1 array between 2 view controllers and successfully print it when I hit a button in the 2nd one.
However, what I really want to do is pass 2 arrays and an Integer, created from a function on the first VC and have them accessible via the 2nd VC.
Code for 1st VC is here :
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController {
destVC.bothArrays = self.testFunction()
}
}
//Get the new view controller using segue.destinationViewController.
//Pass the selected object to the new view controller.
}
func testFunction() -> [String] {
let randomArray1 = ["blah","blah","ploop"]
let randomArray2 = ["alan", "john"]
let randomInt = 5
return BOTH ARRAYS AND INT TO SEND TO THE NEXT VIEW CONTROLLER?
}
#IBAction func goPressed(_ sender: UIButton) {
performSegue(withIdentifier: "goToNextVC", sender: self)
}
and 2nd VC here :
class WorkoutViewController: UIViewController {
var randomArray1 = [String]()
var randomArray2 = [String]()
var randomInt = 0
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func nowButtonPressed(_ sender: UIButton) {
print(randomArray1)
print(randomArray2)
print(randomInt)
}
}
I can get it working with just one array but I need more than one array and a value to be passed! I've tried playing around with it (e.g. trying '-> [String], [String], Int) but no luck
Any help much appreciated!
You can simply use a tuple to include several variables of different types in a single variable. You should pass the tuple including all 3 variables in your performSegue function as the sender argument, then assign them to the relevant instance properties in the prepare(for:) method.
If you want to keep the function for generating the variables, you should change the return type of the function to a tuple that can fit the 3 variables.
func testFunction() -> (arr1:[String],arr2:[String],randInt:Int) {
let randomArray1 = ["blah","blah","ploop"]
let randomArray2 = ["alan", "john"]
let randomInt = 5
return (randomArray1, randomArray2, randomInt)
}
Then assign the return value of testFunction to the sender input argument of performSegue:
performSegue(withIdentifier: "goToNextVC", sender: testFunction())
Assign the variables:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController, let variablesToBePassed = sender as? (arr1:[String],arr2:[String],randInt:Int) {
destVC.randomArray1 = variablesToBePassed.arr1
destVC.randomArray2 = variablesToBePassed.arr2
destVC.randomInt = variablesToBePassed.randInt
}
}
}
As others have suggested, you can refactor your function to return a tuple, and then use that to pass to your other view controller:
//This is the tuple data type we use to pass 2 string arrays and an Int
typealias parameterTuple = ([String], [String], Int)
func testFunction() -> parameterTuple {
let randomArray1 = ["blah","blah","ploop"]
let randomArray2 = ["alan", "john"]
let randomInt = 5
return (randomArray1, randomArray2, randomInt)
}
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToWorkout" {
if let destVC = segue.destination as? WorkoutViewController {
//refactor WorkoutViewController to have a parameters property
//of type parameterTuple, split out the tuple and pass each part to
//a different property in your WorkoutViewController
destVC.parameters = testFunction()
}
}
}
I am trying to perform a segue that passes a number of variables to the next view including one variable, currentID, which is retrieved from a parse database. performSegue should not be called until after currentID has been set to the currentID downloaded from the database. However, when I run the code, currentID ends up being an empty string when it is passed to the next view.
Here is my code called by the Button:
#IBAction func submitButtonPressed(_ sender: Any) {
let point = PFGeoPoint(latitude:0.0, longitude:0.0)
let testObject = PFObject(className: "Person")
testObject["inputAmount"] = inputAmount
testObject["outputAmount"] = outputAmount
testObject["inputCurrency"] = inputCurrency
testObject["outputCurrency"] = outputCurrency
testObject["location"] = point
testObject.saveInBackground { (success, error) -> Void in
// added test for success 11th July 2016
if success {
print("Object has been saved.")
self.currentID = String(describing: testObject.objectId!)
if(self.currentID != ""){
self.performSegue(withIdentifier: "mainToListSegue", sender: self)
}
} else {
if error != nil {
print (error)
} else {
print ("Error")
}
}
}
}
And here is the prepareForSegue method:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let listViewController = (segue.destination as! UINavigationController).viewControllers[0] as! ListViewController
listViewController.inputCurrency = inputCurrency
listViewController.outputCurrency = outputCurrency
listViewController.inputAmount = inputAmount
listViewController.outputAmount = outputAmount
listViewController.currentID = currentID
listViewController.cellContent = cellContent
}
To achieve your needs, you MUST connect your segue between viewcontrollers, and not from UIButton to viewcontroller.
Every time you need to prepare your segue before calling it, this is the procedure:
Then, name it and use delegate method
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "mySegue" {
}
}
For navigating from one controller to another, connect your segue from view controller instead of from the button and it will work.
So here is my code from VC1 and passing the data to VC2.
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
selectedArtist = artists[indexPath.item]
performSegue(withIdentifier: "artistToArtSegue", sender: self)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "artistToArtSegue" {
let artCollectionController = ArtCollectionController()
artCollectionController.artist = selectedArtist
artCollectionController.selectedArtist = selectedArtist
}
}
These codes here in VC2 will print the data
class ArtCollectionController: UICollectionViewController {
var artist = Artist() {
didSet{
print(artist.artistId ?? "did not work")
print(artist.name ?? "what name?")
}
}
var selectedArtist = Artist()
but when I use the the variable in these following test codes in VC2. They return a nil.
func fetchArtForArtist() {
guard let artistId = selectedArtist.artistId else {return}
print(artistId)
let fanRef = FIRDatabase.database().reference().child("art_ref").child(artistId)
fanRef.observeSingleEvent(of: .childAdded, with: { (snapshot) in
let artId = snapshot.key
print(artId)
// let dataRef = FIRDatabase.database().reference().child(artId)
// dataRef.observe(.value, with: { (snapshot) in
// let dictionary = snapshot.value as? [String: AnyObject]
// //let art =
// }, withCancel: nil)
}, withCancel: nil)
}
#IBAction func testButton(_ sender: UIBarButtonItem) {
print(selectedArtist.name ?? "no name")
print(12345)
}
override func viewDidAppear(_ animated: Bool) {
selectedArtist = artist
print(artist.name ?? "non")
print(selectedArtist.artistId ?? "no id")
}
override func viewDidLoad() {
super.viewDidLoad()
fetchArtForArtist()
selectedArtist = artist
print(artist.name ?? "non")
print(selectedArtist.artistId ?? "no id")
}
Im doing this in storyBoard. Im even using 2 vars seeing if there is a difference. I dont understand why the data is successfully passed to VC2 to a couple variables but when the variable is used it returns a nil. Please help.
The other responses are good, but I prefer a slightly different approach:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
switch segue.destination {
case let artCollectionController as ArtCollectionController:
artCollectionController.artist = selectedArtist
artCollectionController.selectedArtist = selectedArtist
case let otherViewController as OtherViewController:
//Code for some other case
}
}
By using a switch statement, you have a prepareForSegue that will handle multiple different segues cleanly.
The case let construct is a cool trick that only executes that case if the variable in the switch can be case to the desired type. If it can be cast, it creates a local variable of the desired type.
I prefer deciding what code to execute based on the class of the destination view controller because it's less fragile than using the segue identifier. If you forget to set the segue identifier, or add a second segue later to the same type of view controller, or have a typo in the name of the identifier, that code won't work. If you have a typo in your class name, though, the compiler throws an error.
Because you set the artist property on a new instance of ArtCollectionController, which is destroyed upon the exit of the prepareForSegue function:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "artistToArtSegue" {
let artCollectionController = ArtCollectionController() // created
artCollectionController.artist = selectedArtist
artCollectionController.selectedArtist = selectedArtist
// destroyed here
}
}
Try this instead:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "artistToArtSegue",
let artCollectionController = segue.destination as? ArtCollectionController
{
artCollectionController.artist = selectedArtist
artCollectionController.selectedArtist = selectedArtist
}
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "artistToArtSegue" {
let artCollectionController = segue.destination as! ArtCollectionController
artCollectionController.artist = selectedArtist
artCollectionController.selectedArtist = selectedArtist
}
}
try this, you are creating one more ArtCollectionController instead of passing data to segue one
sorry for confusing title, but here is my problem. i do a segue from "superVC" (collectionviewcell) to "childVC" and its working well. then i want to segue again from that "childVC" to the "secondChildVC" (which is all the data is from superVC). is it possible? cause i always get a nil value when performing that segue.
its something like this : SuperVC -> ChildVC -> secondChildVC
here is the superVC segue:
var destination = [DestinationData]()
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "DestinationDetailVC"{
let detailVC = segue.destination as? DestinationDetailVC
if let data = sender as? DestinationData{
detailVC?.destinationDetail = data
}
}
}
here is 2nd vc segue
var destinationDetail : DestinationData?
#IBAction func goToMapOnPressed(_ sender: Any) {
let detail = destinationDetail
self.performSegue(withIdentifier: "DestinationMapVC", sender: detail )
print(detail)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "DestinationMapVC"{
let detailVC = segue.destination as? DestinationMapVC
if let data = sender as? DestinationData{
detailVC?.destinationMapDetail = data
}
}
}
Thanks
I think you are sending array of DestinationData to first segue, but inside the first segue you have put condition, so that if the data would be of DestinationData kind class, then the data will be sent to nextVC, But in actual you are sending array of DestinationData object so the if condition fails and hence the data are not passed to childVC
That's why you might be getting nil in the secondChildVC as there is no data in destinationDetail of childVC.
Hence you can modify the condition to check for array as the destination holds array type of data. or else remove the condition from the prepareSegue method.
Code :
//Write this code in to get that clicked object then pass that object in sender
let destTemp = sender[your selected index]
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "DestinationDetailVC"{
let detailVC = segue.destination as? DestinationDetailVC
if let data = sender as? DestinationData{
detailVC?.destinationDetail = data
}
}
}