Why does the second view controller didn´t appear after loading the entry view, but by clicking on a button, he does?
Here is my code:
#IBAction func Pressed(_ sender: UIButton) {
var firstName = FirstName.text;
var lastName = LastName.text;
let defaults = UserDefaults.standard;
defaults.set(firstName, forKey: "FN");
defaults.set(lastName, forKey: "LN");
loadNextView()
}
override func viewDidLoad() {
super.viewDidLoad()
self.FirstName.text = "TESTAUSGABE";
let defaults = UserDefaults.standard;
var fn = defaults.object(forKey: "FN")
var ln = defaults.object(forKey: "LN")
if(fn==nil){
self.FirstName.placeholder="Nicht angegeben"
}
else {
self.FirstName.text = fn as? String
loadNextView()
}
if(ln==nil){
self.LastName.placeholder="Nicht angegeben"
}
else{
self.LastName.text = ln as? String
self.Pressed(self.SaveButton);
}
}
func loadNextView(){
let storyboard: UIStoryboard = UIStoryboard(name:"Main", bundle:nil);
let newViewControler = storyboard.instantiateViewController(withIdentifier: "View2") as UIViewController
self.present(newViewControler, animated: true, completion: nil)
}
I want to check the preferences and if they are already set then it should appear automatically another view.
Or is there another method I didn't know?
Prsenting VCs doesn't work inside viewDidLoad as the view hierarchy is not yet complete , You can try to implement viewDidAppear or viewWillAppear
var runOnce = true
//
override func viewDidAppear(_ animated:Bool){
super.viewDidAppear(animated)
if runOnce {
loadNextView() // here read default value
runOnce = false
}
}
Related
I'm applying for a junior developer position and I've got a very specific task, that already took me 3 days to complete. Sounds easy - pass data to rootViewController.
That's what I've done:
1)
private func userDefaultsToRootController() {
let input = textField.text!
defaults.set(input, forKey: "SavedLabel")
navigationController?.popViewController(animated: true)
}
private func segueToRootViewController() {
let destinationVC = MainScreen1()
let input = textField.text!
if input == "" { self.navigationController?.popToRootViewController(animated: true) }
destinationVC.input = input
navigationController?.pushViewController(destinationVC, animated: true)
}
private func popToNavigationController() {
let input = textField.text!
if let rootVC = navigationController?.viewControllers.first as? MainScreen1 {
rootVC.input = input
}
navigationController?.popToRootViewController(animated: true)
}
I've used CoreData
But here is the difficult part - I've got an email, that all these methods are not good enough and I need to use delegate and closure. I've done delegation and closures before, but when I popToRootViewController delegate method passes nil. Could you at least point where to find info about this?
** ADDED **
There are 2 View Controllers: Initial and Second one.
That's what I have in the Initial View Controller:
var secondVC = MainScreen2()
override func viewDidLoad() {
super.viewDidLoad()
secondVC.delegate = self
}
That's how I push SecondViewController
#objc private func buttonTapped(_ sender: CustomButton) {
let nextViewController = MainScreen2()
navigationController?.pushViewController(nextViewController, animated: true)
}
In SecondViewController I've got this protocol
protocol PassData {
func transferData(text: String)
}
Also a delegate:
var delegate: PassData?
This is how I go back to initial view controller
#objc private func buttonTapped(_ sender: CustomButton) {
if let input = textField.text {
print(input)
self.delegate?.transferData(text: input)
self.navigationController?.popToRootViewController(animated: true)
}
}
Back to the Initial view controller where I've implemented delegate method
extension MainScreen1: PassData {
func transferData(text: String) {
print("delegate called")
label.text = text
}
}
Delegate doesn't get called.
BASED ON YOUR EDIT:
You must set the delegate in buttonTapped
#objc private func buttonTapped(_ sender: CustomButton) {
let nextViewController = MainScreen2()
nextViewController.delegate = self // HERE WHERE YOU SET THE DELEGATE
navigationController?.pushViewController(nextViewController, animated: true)
}
You can delete the second instance and your code in viewDidLoad. That's not the instance you push.
This should point you in the right direction to use delegation and completion handler.
protocol YourDelegateName {
func passData(data:YourDataType)
}
class SecondViewController: UIViewController {
var delegate: YourDelegateName?
func passDataFromSecondViewController(){
YourCoreDataClass.shared.getCoreData { (yourStringsArray) in
self.delegate?.passData(data: yourStringsArray)
self.navigationController?.popToRootViewController(animated: true)
}
}
class InitialViewController: UIViewController, YourDelegateName {
override func viewDidLoad() {
super.viewDidLoad()
// or whenever you instantiate your SecondViewController
let secondViewController = SecondViewController()
secondViewController.delegate = self //VERY IMPORTANT, MANY MISS THIS
self.navigationController?.pushViewController(createVC, animated: true)
}
func passData(data:YourDataType){
//user your data
}
}
class YourCoreDataClass: NSObject {
static let shared = YourCoreDataClass()
func getCoreData (completion: ([String]) -> ()){
........... your code
let yourStringsArray = [String]() // let's use as example an array of strings
//when you got the data your want to pass
completion(yourStringsArray)
}
}
Im having button in all viewcontrollers to change language
LanguageViewController.swift
class LanguageViewController: UIViewController {
#IBAction func actionChange(_ sender: Any) {
L102Language.currentAppleLanguage()
L102Language.setAppleLAnguageTo(lang: "en")
// below code to refresh storyboard
self.viewDidLoad()
}
}
L102Language.swift
class func currentAppleLanguage() -> String{
let userdef = UserDefaults.standard
let langArray = userdef.object(forKey: APPLE_LANGUAGE_KEY) as! NSArray
let current = langArray.firstObject as! String
let endIndex = current.startIndex
let currentWithoutLocale = current.substring(to: current.index(endIndex, offsetBy: 2))
return currentWithoutLocale
}
/// set #lang to be the first in Applelanguages list
class func setAppleLAnguageTo(lang: String) {
let userdef = UserDefaults.standard
userdef.set([lang,currentAppleLanguage()], forKey: APPLE_LANGUAGE_KEY)
userdef.synchronize()
}
I inherited LanguageViewController in all my FirstViewCOntroller, SecondController as below
class FirstViewController: LanguageViewController {
}
class SecondController: LanguageViewController {
}
If I call self.viewDidLoad() it fails to change language from view defined in storyboard. How to reload storyboard, so that the language should change in all viewcontroller,if any button from any viewcontroller is clicked? Thanks!
You can use NotificationCenter for reloading the view controllers content, this will also reload the content of view controllers that are not visible.
extension Notification.Name {
static let didChangeLanguage = Notification.Name("didChangeLanguage")
}
override func viewDidLoad() {
//Add a listener
NotificationCenter.default.addObserver(self, selector: #selector(onDidChangeLanguage(_:)), name: .didChangeLanguage, object: nil)
}
#IBAction func actionChange(_ sender: Any) {
L102Language.currentAppleLanguage()
L102Language.setAppleLAnguageTo(lang: "en")
// Notify about the change.
NotificationCenter.default.post(name: .didChangeLanguage, object: self, userInfo: nil)
}
#objc func onDidChangeLanguage(_ notification:Notification) {
// reload content using selected language.
}
Correct me if I'm wrong. but I think you don't need to reload all view controllers. you just need to update them when they get displayed, view controllers are behind the presented one are not visible for the user.
for doing that you can do something like this:
var currentLanguage = ""
override func viewDidLoad() {
currentLanguage = currentAppleLanguage()
loadContentForLanguage(currentLanguage)
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
// this will be executed every time this sceen gets display
if currentLanguage != currentAppleLanguage() {
currentLanguage = currentAppleLanguage()
loadContentForLanguage(currentLanguage)
}
}
func loadContentForLanguage(_ currentLanguage: String) {
//here it goes whatever you currently have in viewDidLoad
}
My apologies if this does not compile, my swift is really rusty.
I am trying to implement a "always logged in" function in to my app. The problem is that if I restart my app, it crashes. This is what I did:
set Userdefault:
#objc func loginButtonTapped(_ sender: Any) {
let email = self.emailTextField.text!.trimmingCharacters(in: .whitespacesAndNewlines)
let password = self.passwordTextField.text!.trimmingCharacters(in: .whitespacesAndNewlines)
// start button animation
loginButton.startAnimation()
let qualityOfServiceClass = DispatchQoS.QoSClass.background
let backgorundQueue = DispatchQueue.global(qos: qualityOfServiceClass)
backgorundQueue.async {
// check if account details correct
Auth.auth().signIn(withEmail: email, password: password) { (result, error) in
if error != nil {
DispatchQueue.main.async {
// error -> stop animation
self.loginButton.stopAnimation(animationStyle: .shake, revertAfterDelay: 0) {
self.errorLabel.text = error!.localizedDescription
self.errorLabel.alpha = 1
}
}
}else {
// correct acount details -> login
DispatchQueue.main.async {
UserDefaults.standard.set(true, forKey: "isLoggedIn")
UserDefaults.standard.synchronize()
// transition to home ViewController
self.transitionToHome()
}
}
}
}
}
checking UserDefault:
class MainNavigationControllerViewController: UINavigationController {
override func viewDidLoad() {
super.viewDidLoad()
if isLoggedIn() {
let homeController = MainViewController()
viewControllers = [homeController]
}
}
fileprivate func isLoggedIn() -> Bool {
return UserDefaults.standard.bool(forKey: "isLoggedIn")
}
}
The user logs in via Firebase and all the data is stored in Cloud Firestore.
Error
cell.customWishlistTapCallback = {
let heroID = "wishlistImageIDX\(indexPath)"
cell.theView.heroID = heroID
let addButtonHeroID = "addWishButtonID"
self.addButton.heroID = addButtonHeroID
// track selected index
self.currentWishListIDX = indexPath.item
let vc = self.storyboard?.instantiateViewController(withIdentifier: "WishlistVC") as? WishlistViewController
vc?.wishList = self.dataSourceArray[self.currentWishListIDX]
// pass drop down options
vc?.theDropDownOptions = self.dropDownButton.dropView.dropDownOptions
vc?.theDropDownImageOptions = self.dropDownButton.dropView.dropDownListImages
// pass current wishlist index
vc?.currentWishListIDX = self.currentWishListIDX
// pass the data array
vc?.dataSourceArray = self.dataSourceArray
// set Hero ID for transition
vc?.wishlistImage.heroID = heroID
vc?.addWishButton.heroID = addButtonHeroID
// allow MainVC to recieve updated datasource array
vc?.dismissWishDelegate = self
vc?.theTableView.tableView.reloadData()
self.present(vc!, animated: true, completion: nil)
}
Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)
at line:
let vc = self.storyboard?.instantiateViewController(withIdentifier: "WishlistVC") as! WishlistViewController
I guess it is not as easy as I thought. Does anyone know why the app crashes and how I can solve this? :)
You are creating your MainViewController instance using a simple initialiser (MainViewController()) rather than instantiating it from the storyboard. As a result, any #IBOutlet properties will be nil since it is the the storyboard process that allocates those object instances and assigns them to the properties.
You need to add an identifier to your main view controller scene (if it doesn't already have one) and use that to instantiate the view controller instance. E.g. assuming the scene identifier is "MainScene" you would have something like:
override func viewDidLoad() {
super.viewDidLoad()
if isLoggedIn() {
let homeController = UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier("MainScene")
viewControllers = [homeController]
}
}
The crash in your updated question indicates that either the scene with the identifier WishlistVC doesn't have its class set to WishlistViewController or it isn't found so the forced downcast crashes.
I have two ViewControllers, each with one TextField to get user input number and two buttons to calculate and navigate.
The instance of TextField in the SecondVC is created by user when filling the TextFields and it exists and it is shown in the View
The problem is: when you leave the SecondView Controller after creating the object - Cell and you come back to it later, it is set back to cero, which is not the instance - Cell value
class MainViewController: UIViewController {
#IBOutlet weak var A3TextField: UITextField!
#IBAction func calc(_ sender: Any) {
let A3 = Cell(name: "A3", sheet: "", value: Double(A3TextField.text!)!)
print(A3)
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
}
class SecondViewController: UIViewController {
#IBOutlet weak var B3TextField: UITextField!
#IBAction func calc2(_ sender: Any) {
let B3 = Cell(name: "B3", sheet: "", value: Double(B3TextField.text!)!)
print(B3)
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}
struct Cell {
var name: String = ""
var sheet: String = ""
var value: Double = 0
init(name: String, sheet: String, value: Double) {
self.name = name
self.sheet = sheet
self.value = value
}
}
When controller pop or push ,their temporary property value or object can not be save to other controller,even in itself controller ,when push and back ,their are the init value,if you want save value when page switching，suggest these solution:
1. Pass throw the attribute values(one => two)
OneViewController:
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let twoVC = storyboard.instantiateViewController(withIdentifier: "TwoViewControllerID") as! twoViewController
twoVC.myStr="Controller one to controller two!"
self.present(twoVC, animated: true, completion: nil)
TwoViewController
var myStr=String()
override func viewDidLoad() {
super.viewDidLoad()
print("get value：\(myStr)"
}
2, use NSUerDfault to save and get
SetValue:
let userDefault = UserDefaults.standard
userDefault.set(name, forKey: "name")
userDefault.synchronize()
GetValue:
let userDefault = UserDefaults.standard
let name = userDefault.object(forKey: "name") as? String
3,storybord pass value(one => two)
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let theSegue=segue.destination as! twoViewController theSegue.myStr="other pass way" }
4,deleagte pass value(two => one)
based don back to front page
TwoViewController:
//(1)create a delegate before class
protocol FTVCdelegte : NSObjectProtocol{
//define method
// one method
func change(title:String)
//two method
func ChangeColoer (Coloer:UIColor)
//three method
func ChangSucces(YON:Bool)
}
//(2)create delegate object。
var delegate_zsj:FTVCdelegte?
//(3)click back button
#IBAction func backBtnAction(_ sender: UIButton) {
delegate_zsj?.change(title: "main page")
delegate_zsj?.ChangeColoer(Coloer: UIColor.red)
delegate_zsj?.ChangSucces(YON: true)
self.navigationController?.popViewController(animated: true)
}
OneViewController
//(4)inherit delegate：
class SecondViewController: UIViewController,FTVCdelegte,ChangeBtnDelege{
...
//(5)imple delegate method
func change(title: String) { self.title = title }
func ChangeColoer(Coloer: UIColor) { self.view.backgroundColor = Coloer }
func ChangSucces(YON: Bool) { print(YON) }
//(6)when pop page use
#IBAction func tiaozhuanBtnAction(_ sender: Any) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let oneVC = storyboard.instantiateViewController(withIdentifier: "OneViewControllerID") as! oneViewController
oneVC.delegate_zsj = self
self.navigationController?.pushViewController(oneVC, animated: true)
}
5,block pass value(two => one)
based don back to front page
TwoViewController:
//(1)define a block method：
var bbchange:((_ title:String,_ myColor:UIColor)->Void)?
//(2)back to front page：
#IBAction func backBtnAction(_ sender: UIButton) {
bbchange?("document",UIColor.green)
self.navigationController?.popViewController(animated: true)
}
OneViewController
//(3)next page invoke block method
#IBAction func tiaozhuanBtnAction(_ sender: Any) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let threeVC = storyboard.instantiateViewController(withIdentifier: "twoViewControllerID") as! twoViewController
twoVC.bbchange=
{
( title:String,myColor:UIColor) in
self.title=title
self.view.backgroundColor=myColor
}
self.navigationController?.pushViewController(twoVC, animated: true)
}
I am looking at adding an inital note to the note page within my app. this is so that when people click to the notes part there will be some detail on how to use it rather than just a big empty screen. I have no idea where to implement this though. Could you please help, below is the page where it talks about the dictionaries.
import UIKit
import MessageUI
class DetailViewController: UIViewController, MFMailComposeViewControllerDelegate, UITextViewDelegate {
#IBOutlet weak var tView: UITextView!
#IBAction func BarButton(sender: UIBarButtonItem) {
let textToShare = ""
if let myWebsite = NSURL(string: "")
{
let objectsToShare = [textToShare, myWebsite]
let activityVC = UIActivityViewController(activityItems: objectsToShare, applicationActivities: nil)
self.presentViewController(activityVC, animated: true, completion: nil)
}
OpenMail()
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
tView.text = (allNotes[currentNoteIndex] as Note).note
tView.becomeFirstResponder()
// Set controller as swipe gesture recogniser, to allow keyboard dismissal for text box
var swipe: UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "dismissKeyboard")
swipe.direction = UISwipeGestureRecognizerDirection.Down
self.view.addGestureRecognizer(swipe)
self.tView.delegate = self
}
override func viewWillDisappear(animated: Bool) {
super.viewWillDisappear(animated)
if tView.text == "" {
allNotes.removeAtIndex(currentNoteIndex)
}
else {
(allNotes[currentNoteIndex] as Note).note = tView.text
}
Note.saveNotes()
noteTable?.reloadData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func configuredMailComposeViewController() -> MFMailComposeViewController {
// Open mail controller on screen and prepare with preset values.
let mailComposerVC = MFMailComposeViewController()
var MessageText: String!
MessageText = tView.text
mailComposerVC.mailComposeDelegate = self
mailComposerVC.setToRecipients([""])
mailComposerVC.setSubject("")
mailComposerVC.setMessageBody(MessageText, isHTML: false)
return mailComposerVC
}
func showSendMailErrorAlert() {
// Alert user to email error
let sendMailErrorAlert = UIAlertView(title: "Could Not Send Email", message: "Your device could not send e-mail. Please check e-mail configuration and try again.", delegate: self, cancelButtonTitle: "OK")
sendMailErrorAlert.show()
}
// MARK: MFMailComposeViewControllerDelegate Method
func mailComposeController(controller: MFMailComposeViewController!, didFinishWithResult result: MFMailComposeResult, error: NSError!) {
controller.dismissViewControllerAnimated(true, completion: nil)
}
func OpenMail() {
//Function to open mail composer on screen
let mailComposeViewController = configuredMailComposeViewController()
if MFMailComposeViewController.canSendMail() {
self.presentViewController(mailComposeViewController, animated: true, completion: nil)
} else {
self.showSendMailErrorAlert()
}
}
func dismissKeyboard() {
// Dismiss keyboard for textfield
self.tView.resignFirstResponder()
}
}
note.swift
import UIKit
var allNotes:[Note] = []
var currentNoteIndex:NSInteger = -1
var noteTable:UITableView?
let KAllNotes:String = "notes"
class Note: NSObject {
var date:String
var note:String
override init() {
date = NSDate().description
note = ""
}
func dictionary() -> NSDictionary {
return ["note":note, "date":date]
}
class func saveNotes() {
var aDictionaries:[NSDictionary] = []
for (var i:NSInteger = 0; i < allNotes.count; i++) {
aDictionaries.append(allNotes[i].dictionary())
}
NSUserDefaults.standardUserDefaults().setObject(aDictionaries, forKey: KAllNotes)
// aDictionaries.writeToFile(filePath(), atomically: true)
}
class func loadnotes() {
allNotes.removeAll(keepCapacity: true)
var defaults:NSUserDefaults = NSUserDefaults.standardUserDefaults()
var savedData:[NSDictionary]? = defaults.objectForKey(KAllNotes) as? [NSDictionary]
// var savedData:NSArray? = NSArray(contentsOfFile: filePath())
if let data:[NSDictionary] = savedData {
for (var i:NSInteger = 0; i < data.count; i++) {
var n:Note = Note()
n.setValuesForKeysWithDictionary(data[i] as [NSObject : AnyObject])
allNotes.append(n)
}
}
}
class func filePath() -> String {
var d:[String]? = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true) as? [String]
if let directories:[String] = d {
var docsDirectory:String = directories[0]
var path:String = docsDirectory.stringByAppendingPathComponent("\(KAllNotes).notes")
return path;
}
return ""
}
}
Thanks in advance
Sam
Add an NSUserDefault boolean that stores whether or not the initial note should be shown, e.g. that the app has been launched for the first time. Then load an initial note accordingly. When a note is added or the initial note is deleted, then change the boolean accordingly so the initial note doesn't show up next time.
You could also initialize your database with an initial note. Not clear from your code how the notes are saved, but this approach would probably rely on the NSUserDefault approach above, except it could be done in the AppDelegate or something.
example:
let InitialSetupComplete = "InitialSetupComplete" // Note: I would define this at the top of a file
let defaults = NSUserDefaults.standardUserDefaults()
if defaults.boolForKey(InitialSetupComplete) {
// Show initial note
}
// Later on when the note is deleted, or modified (or immediately after initial note loaded into the database, see below)
defaults.setBool(true, forKey: InitialSetupComplete)
Would be easier/cleaner just to initialize your database with the initial note in the app delegate (e.g. call within applicationDidFinishLaunching), so your view controller doesn't have to figure this out. Similar code, except you would use setBool right away after the initial note has been saved to the database. I don't know anything about your database from the question, so can't really provide a more detailed example than this. Hope this helps.