I have two view controllers and in ViewController 1 I have a date picker and a text field. I have another ViewController that displays what you have entered in that date picker and text field. I have a ¨change¨ button that returns you to that first view controller and a ¨doen¨button that show view controller 2. As of now the text in the textfield and the date that the user has selected, is gone every time you close the app or click the ¨change button(Go back to View controller 1).
How can i keep the text in the text field, and the selected date in the date picker.
I want the user to be able to change the information that has already been added.
Please add code.
http://imgur.com/PDzJrNJ (Picture of the main storyboard)
The way you are showing the ViewControllers is not optimal. In the best case, when you show something new (ViewController2), then dismiss it, it should lead you back to the previous screen (ViewController1). It should not instantiate a new instance of ViewController1, as the segues in you case are doing.
Please note that depending on how you present the second view the solution would be different.
In case your segue from the first controller to the second is a "Show" segue, you can just add the following to your "Change" button:
#IBAction func changeButtonPressed(sender: AnyObject) {
self.dismissViewControllerAnimated(true, completion: nil)
}
In case you have a navigation controller (I do not see such on the screenshot), then you can use
#IBAction func changeButtonPressed(sender: AnyObject) {
self.navigationController.popViewControllerAnimated(true)
}
What you could try doing is saving the data before exiting the view controller.
In the viewWillDisappear method, you could add
NSUserDefaults.standardUserDefaults().setObject(textField.text, forKey: "userText")
NSUserDefaults.standardUserDefaults().setObject(datePicker.date, forKey: "userDate")
Later, when you reopen the same view controller, in the viewDidLoad method, you could add
if NSUserDefaults.standardUserDefaults().objectForKey("userText") != nil {
textField.text = NSUserDefaults.standardUserDefaults().objectForKey("userText") as! String
}
if NSUserDefaults.standardUserDefaults().objectForKey("userDate") != nil {
datePicker.setDate(NSUserDefaults.standardUserDefaults().objectForKey("userDate") as! NSDate, animated: true)
}
I do not use date pickers very frequently, but I believe this is the correct code. Otherwise, it would be very similar. Hope this helps.
Related
i have a outline view with a custom cell.
all works fine but i need to know, if a button was pressed, in which row number the that button is.
how can i get this row number ?
You could wire up your button's action to an IBAction in your view controller (or whatever knows about the outline view) and call row(for:) on the outline view:
#IBAction func buttonClicked(_ sender: NSButton) {
print("button row:", outlineView.row(for: sender))
}
Straight from the docs:
This method is typically called in the action method for an NSButton
(or NSControl) to find out what row (and column) the action should be
performed on.
I have some quite simple doubt regarding optional binding,global variable & wrapping and unwrapping . Since I am new to SWIFT, its very important to understand the tits & bits of their concepts.
1) In Swift if I declare a global variable, I have 2 options either to make it optional or non optional, so let I am having 2-4 or more optional variables . So is it advisable to optional bind all those variables in
viewDidLoad() method// so that I could use them without any problem of unwrapping and fatal error in my program.
2) Let me make myself more clear by the following example- I have 2 VC in my project VC1 & VC2 . VC2 has a text field in which user enters some value and displays it in a tabelview in VC1.
In Vc1
var namevc1 = NSMutableArray?//holds the input of textfield to be passed from VC2.
As you can see, my VC1 is the first view controller that loads when my project runs and I am using an optional variable to populate my tabke vuew that is
'arr'
So when the app runs for the first time its empty . So it might cause a fatal error while using its value in the code. So what is its solution whether to unbind it in the
viewDidLoad()
method or in all total declare an empty NSMutable array type in place of optional type .
Thanks in advance.
I'll start by repeating the my comment from above.
Possibly you've misunderstanding the concept of global variables in Swift.
If you have a global variable, you won't have to "pass" it between any views/methods/classes etc, because the variable is defined at global scope (accessible everywhere).
Generally global variables is not a good idea, and something that you want to avoid.
Regarding the matter of global variables and swift, you really should include singletons into the discussion. See e.g. the following existing SO thread(s):
Any reason not use use a singleton "variable" in Swift?
(How to create a global variable?)
(Declaring Global Variables in Swift)
Communication between TableViewController and ViewController by means of segues (prepare for & unwind segues)
(This answer ended up being very and probably a bit too thorough, as I didn't know in detail what your current tableview/viewcontroller program state looks like. Sorry for the lengthy answer and any inconvenience it might bring to readers of it).
Now, lets leave global variables and discuss one (among other) viable options for the communication between the two controllers in your example. From your question, I'll summarize your example as follows
VC1: storyboard entry point, a UITableViewController consisting of UITableViewCells, where, in these cells, you display some text, say, via instances of UILabel.
VC2: a UIViewController, accessible from the cells of VC1, containing an UITextField instance. When user enters text into this text field, your want the text to be displayed in the associated cell in VC2 (associated in the sense that it was the cell in VC1 that was used to access VC2).
We'll associate VC1 and VC2 with (cocoa touch) classes TableViewController (TableViewController.swift) and ViewController (ViewController.swift), respectively. The cells in the table view controller will be associated with (cocoa touch) class TableViewCell (TableViewCell.swift). Details for these classes follow below.
For this simple example, note that we will not embed VC1 into a navigation controller (which is otherwise appropriate for table view -> view navigation).
We'll start in the storyboard, adding objects (drag-and-drop from object library) for a Table View Controller and a View Controller. The table view container will also, automatically, contain, in its Table View, a TableViewCell. Continuing in the storyboard:
Add a UILabel object to the TableViewCell container in the Table View Controller (align it as you wish)
In the View Controller, add a Text Field object and a Button object (align them as you wish).
Set the entry point to the Table View Controller.
Thereafter Ctrl-drag a 'Show' segue from the TableViewCell to the View Controller.
Select the Show segue and, from the Attributes inspector, enter an identifier for it, say, ShowDetail.
Finally, with the TableViewCell selected, (as above; from the attribute inspector), enter an identifier for the cell. Here, we'll use simply use identifier TableViewCell.
We now leave the storyboard for now and implement three classes, associated with the Table View Controller, the View Controller and the formers' TableViewCell.
We start with the Table View Controller, and implement our UITableViewController sub-class. Note that here, instead of using an NSMutableArray to hold the texts of the UITextLabel in each cell, we'll simply use a String array.
// TableViewController.swift
Import UIKit
class TableViewController: UITableViewController {
// Properties
var userTextLabels = [String]()
var numberOfCells: Int?
override func viewDidLoad() {
super.viewDidLoad()
numberOfCells = loadSampleTextLabels() // Load sample labels.
}
func loadSampleTextLabels() -> Int {
userTextLabels += ["Label #1", "Label #2", "Label #3"]
return userTextLabels.count
}
// func numberOfSectionsInTableView(tableView: UITableView) ...
// func tableView(tableView: UITableView, numberOfRowsInSection section: Int) ...
override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cellIdentifier = ("TableViewCell")
let cell = tableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath: indexPath) as! TableViewCell
// Text for current cell
let cellText = userTextLabels[indexPath.row]
cell.userSuppliedTextLabel.text = cellText
return cell
}
// ... communication?
}
Where the two commented out methods are standard methods used in any UITableViewController, for number of sections (e.g. return 1) and cells (e.g. return (numberOfCells ?? 0)) in the table, respectively. I'll leave fixing these to you.
Now, we associate the TableViewCell object(s) in the table view with instances of a subclass to UITableViewCell. Here, we'll use a very simple class for our cells; each cell just containing a single UILabel instance (created via storyboard Ctrl-drag as an #IBOutlet from the UILabel in the table view cells).
// TableViewCell.swift
import UIKit
class TableViewCell: UITableViewCell {
// Properties
#IBOutlet weak var userSuppliedTextLabel: UILabel!
// Ctrl-drag from UILabel (in TableViewCell) in storyboard
override func awakeFromNib() {
super.awakeFromNib()
}
override func setSelected(selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
}
}
Finally, for the view controller that is accessed from the table view cells: use a single #IBOutlet to the UITextField used for user text input, and handle events in this text field using the pre-existing UITextFieldDelegate. E.g.:
// ViewController.swift
import UIKit
class ViewController: UIViewController, UITextFieldDelegate {
// Properties
#IBOutlet weak var userSuppliedText: UITextField!
// Ctrl-drag from storyboard...
var cellText: String?
override func viewDidLoad() {
super.viewDidLoad()
userSuppliedText.text = cellText ?? "..."
// Handle the user input in the text field through delegate callbacks
userSuppliedText.delegate = self
}
// UITextFieldDelegate
func textFieldShouldReturn(textField: UITextField) -> Bool {
// User finished typing (hit return): hide the keyboard.
textField.resignFirstResponder()
return true
}
func textFieldDidEndEditing(textField: UITextField) {
cellText = textField.text
}
}
We've also declared a string property (cellText) here, that will as act as container for communication between VC1 and VC2.
We return to the storyboard and---from the Identity inspector---associate the three storyboard objects (Table View Controller, View Controller, TableViewCell) with their associated classes that we've just written above.
We're now almost at our goal; it only remains to specify how to communicate between the two controllers.
We'll begin with communication from VC1 to VC2. In your comment above, you were on the right track (for this specific solution, anyway) by looking at the prepareForSegue(...) method. In the class for the Table View Controller, we add the following method:
// ... add to TableViewController.swift
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
if segue.identifier == "ShowDetail" {
let viewController = segue.destinationViewController as! ViewController
if let selectedCell = sender as? TableViewCell {
let indexPath = tableView.indexPathForCell(selectedCell)!
let currentTextInCell = userTextLabels[indexPath.row]
viewController.cellText = currentTextInCell // <-- note this
}
}
}
Hence, for VC1->VC2 communication, we can (in this example) bring whatever existing text that is currently occupying the UILabel in the sender cell (as is specified by the String array userTextLabels). Look at the viewDidLoad(...) method in the ViewController.swift to see how this value is passed from VC1 and set as default text in the UITextField in VC2.
Now, for communication VC2->VC1, which was the specific communication direction you were asking about, add another method (programmatically), again to TableViewController.swift:
// ... add to TableViewController.swift
#IBAction func unwindToTableView(sender: UIStoryboardSegue) {
if let sourceViewController = sender.sourceViewController as? ViewController,
text = sourceViewController.cellText {
// ^ note 2nd clause of if let statement above
if let selectedIndexPath = tableView.indexPathForSelectedRow {
// Update cell text
userTextLabels[selectedIndexPath.row] = text
tableView.reloadRowsAtIndexPaths([selectedIndexPath], withRowAnimation: .None)
}
}
}
Here, we define an unwind action that, when triggered, retrieves the cellText property of the view controller that was the source of the segue, i.e., in our case, the instance of ViewController. But how do we trigger this action?
Return to the storyboard and the View Controller. Note the three little icons in the top of the View Controller object, more specifically, the right-most of these, named Exit. Ctrl-drag an action from your Button to the Exit icon, and select the unwindToTableView Action Segue. When you click your button the view controller, the view unwind (exit) and land at the unwindToTableView method in the TableViewController.
The resulting app should look something like this:
This was way longer than I had expected, but once you get started writing... Anyway, the method above uses, naturally, no global variables, but make use of references to future (prepareForSegue) or historic (unwindToTableView) views to get (generally from current or historic view) or set (generally in current of future view) values by using these references (to future/historic view).
Apple has their own very thorough tutorial on an example app in the tableviewcontroller/viewcontroller context that I would recommend going over. I found it very valuable myself when I started coding Swift.
Start Developing iOS Apps (Swift)
Ok so here is my question.
I want to have a screen pop up right after my LaunchScreen exits and i want to be able to add information into it, however once I add that information into it, I do not want to see that screen again.
I will be using storyboard, swift and CoreData and Xcode 6.3 if that helps.
Thanks in advanece
NSUserDefaults is a really quick way of storing (small amounts of) data.
let defaults = NSUserDefaults.standardUserDefaults()
defaults.setBool(true, forKey: "hasSeenStartup")
if(defaults.boolForKey("hasSeenStartup")){
println("Don't show")
}
First you will need to define a set of userDefaults, easiest is standardUserDefaults()
We can set a boolean value to a key (after we showed the popup screen) using setBool() this takes 2 parameters, the first is the boolean value, the second is a key for the value.
When the users launches the app, you will need to get the boolean value for the key. If the user already has seen the popup (it’s boolean value for hasSeenStartup will be set to true) you can skip the popup and show them the other viewController
EDIT:
Since your question seems to focus on showing the new view controller rather than saving the data. Here is some code on how to show a new view controller.
let storyboard:UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc: NewViewControllerClass = storyboard.instantiateViewControllerWithIdentifier(“newViewController") as! NewViewControllerClass
self.presentViewController(vc, animated: true, completion: nil)
To use this code you will need to change the:
Storyboard name to the name of your storyboard (defaults to “Main”)
Set the class of the viewController by replacing NewViewControllerClass with the class of (obviously) your new viewController.
Change the newViewController with the Identifier
You can than use this code to present the new ViewController. Present this viewController if your Core Data has info saved about the user and thus if the user has seen the initial screen.
I would advice to retrieve the Core Data inside the ViewDidAppear method inside your FirstViewController.
override func viewDidAppear(animated: Bool) {
if (check to see if core data is not empty){
let storyboard:UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
let vc: NewViewControllerClass = storyboard.instantiateViewControllerWithIdentifier(“newViewController") as! NewViewControllerClass
self.presentViewController(vc, animated: true, completion: nil)
}
}
(Xcode6-beta3, Swift, iOS8, iPad)
In an iPad split-view controller, how do I link the Master View Controller to the Detail View Controller?
In other words, when the user taps on an item on the left, how do I change the view on the right?
I know that in didSelectRowAtIndexPath, I need to call a method... but how do I call a method in the Detail View Controller from the Master View Controller?
Example
Imagine an app to display information on different types of cheeses. We begin by dragging a split-view controller onto the storyboard. A table of items in the master view on the left is set up to read as follows.
Swiss
Cheddar
Brie
On the right, there is simply a Web View inside of the detail view controller, named cheeseViewController. Therein, HTML documents about the selected cheese will be displayed.
An IBOutlet is wired from the web view into cheeseViewController, and a method named 'changeCheese' is set up in the Detail View Controller delegate to swap out the document.
How can I make a tap on "Cheddar" change the information in the detail view?
EDIT: Do I have to modify my AppDelegate.swift file? Using a Master-Detail template, I tried the following, with no luck:
func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool {
// Override point for customization after application launch.
let splitViewController = self.window!.rootViewController as UISplitViewController
let navigationController = splitViewController.viewControllers[splitViewController.viewControllers.count-1] as UINavigationController
splitViewController.delegate = navigationController.topViewController as Paragraph
return true
}
I hope I understood your problem correctly: You would like to show the detail information of a selected cheese in your Detailview.
When you create a new Master-Detail-View application in XCode 6 Beta 3, there will be a variable called "detailItem" in your DetailViewController.Swift file:
var detailItem: AnyObject? {
didSet{
self.configureView()
}
You set this detailItem in your MasterViewController.Swift file in the following function:
override func prepareForSegue(segue: UIStoryBoardSegue, sender: AnyObject?){
if segue.identifier == "yourSegueIdentifier" {
let indexPath = self.tableView.indexPathForSelectedRow()
let cheeese = yourCheeseArrayWithDetailInformation[indexPath.row]
(segue.destinationViewController as DetailViewController).detailItem = cheeese
}
}
(Assuming, that you have linked the views with a segue with the identifier: "yourSegueIdentifier" and an array of detailinfo called "yourCheeseArrayWithDetailInformation")
The above mentioned function "configureView" in the DetailView can now access your detailItem, which contains the contents of "cheeese"
I hope this helps you.
Why don't you just post a Notification from didSelectRowAtIndexPath in your Master and add an observer in your Detail View most likely inside your viewDidLoad. You also can handle the selector within the observer method with closure.
If you didn't create a master-detail app (so you have no detailItem), you might use this:
if let
mySplitViewController = splitViewController,
detailView = mySplitViewController.childViewControllers.last as? DetailViewController {
// do something with it
}
First of all, let me say I'm an absolute beginner, so please forgive me if this is a stupid questions to be asking. And let me just add that I've spent hours/days trying to figure out how to solve this problem - including extensive searches on stackoverflow (maybe the answer is somewhere and I just don't now exactly what to search for :)...
But, let's continue: I have a small (?) problem with an Xcode storyboard project. Basically my project looks like this:
Navigation Controller -> View Controller 0 -> Tab Bar Controller -< View Controller 1, View Controller 2, View Controller 3.
When the user pushes 'button #2' in the View Controller 0, I'd like him/her to jump directly to 'View Controller 2'.
Would that be possible at all, and if so what code should use and excatly where should I put it.
Hope someone out there will help a newbie out :)
Regards,
Ulrik
Yes it is possible. You may show any view controller from any other.
You should simply add a segue from button #2 to View Controller 2. (I assume you have all your controllers in single storyboard)
Update: the above solution will show you View Controller 2 itself without tab bar controller.
Hard to tell in details without seeing the actual code. For more details you may refer to these documents:
View Controller Basics (especially part "Storyboards Help You Design Your User Interface")
Presenting View Controllers from Other View Controllers
Using View Controllers in Your App
Probably you'll come up with more concrete question.
Update
If you want to preselect desired view controller inside tabbar controller you may use the following code sketch. Here you can programmatically initiate a segue and do the desired pre-initialization inside prepareForSegue:sender: method.
static NSString * const kShowTabSegueID = #"ShowTab";
#interface ViewController ()
- (IBAction)buttonOnePressed;
- (IBAction)buttonTwoPressed;
- (IBAction)buttonThreePressed;
#end
#implementation ViewController
- (IBAction)buttonOnePressed
{
[self performSegueWithIdentifier:kShowTabSegueID
sender:#0];
}
- (IBAction)buttonTwoPressed
{
[self performSegueWithIdentifier:kShowTabSegueID
sender:#1];
}
- (IBAction)buttonThreePressed
{
[self performSegueWithIdentifier:kShowTabSegueID
sender:#2];
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue
sender:(id)sender
{
if ([segue.identifier isEqual:kShowTabSegueID]) {
NSNumber *indexToShow = sender;
UITabBarController *tabBar = segue.destinationViewController;
[tabBar setSelectedIndex:indexToShow.unsignedIntegerValue];
}
}
#end
If you are simply trying to programatically switch tabs, its as simple as:
[self.tabBarController setSelectedIndex:1];
If I am understanding your flow correctly, from ViewController0 you would present ViewController1(that has a UITabBarController). In the viewWillAppear: set the selectedIndex for the tab controller (code above) to index 1, which would be ViewController2.
EDIT
After looking at your project, add this code to your BrainBreaksViewController.m
- (void)viewWillAppear:(BOOL)animated
{
[self.tabBarController setSelectedIndex:1];
}
I added this, and it switches to the 2nd tab after pressing "Press this button to goto tab #1". Follow Max Ks answer if you would like to be able to have a button to open each specific tab.
So if I understand correctly you have a view controller outside the tabbar controller and you want to navigate to the second tab in the tabbar controller from that (outside)view controller, if that is the problem then, this is my solution and I hope it helps someone as I spent some time on this issue myself.
First connect the (outside)Viewcontroller 0 to the tabbar controller in the storyboard with modal segue and give it identifier - "showTabBar" (not as one of the tabs just a modal segue).
Then:
in Viewcontroller 0 declare:
var tabBarIndex: Int?
//function that will trigger the **MODAL** segue
private func loadTabBarController(atIndex: Int){
self.tabBarIndex = atIndex
self.performSegue(withIdentifier: "showTabBar", sender: self)
}
//in here you set the index of the destination tab and you are done
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showTabBar" {
let tabbarController = segue.destination as! UITabBarController
tabbarController.selectedIndex = self.tabBarIndex!
}
}
then you can navigate to ViewController 2 like that(don't forget it is 0 indexed):
self.loadTabBarController(atIndex: 1)
This is tested and working as of the day I am posting this answer using
Swift 3.0.2 / Xcode 8.2.1