I want to use the NSStackView to stack views above each other, I also want them to de able to expand so I can't use the NSCollectionView if i understood it correctly.
So, in storyboard, I've created a NSStackView(embedded in scroll view) in the main view controller and a view controller that I want to fill it with:
The button will fill the stack view with ten views:
#IBOutlet weak var stackView: NSStackView!
#IBAction func redrawStackView(_ sender: Any) {
for i in 0..<10 {
let stackViewItemVC = storyboard?.instantiateController(withIdentifier: "StackViewItemVC") as! StackViewItemViewController
stackViewItemVC.id = i
stackView.addArrangedSubview(stackViewItemVC.view)
}
}
And the ViewController on the right simply looks like this:
class StackViewItemViewController: NSViewController {
var id: Int = -1
override func viewDidLoad() {
super.viewDidLoad()
// Do view setup here.
}
#IBAction func buttonPressed(_ sender: Any) {
debugPrint("StackViewItemViewController" + id.description + "pressed")
}
Running this small application works fine, every time I press the button ten more stack view items appears. But, when I have the audacity to press one of the buttons to the right the application crashes:
Where am I going wrong?
I have tried to work around the IBAction to verify that this what breaks, and the application will not crash if I subclass the button and make a "buttonDelegate" protocol with a function being called from mouseUp.
I guess the problem is that the viewController objects, which you create in the loop, are released immediately.
Even though the view is attached to the stackView, it's viewController is destroyed.
You can fix this issue by keeping a reference to each viewController.
You can do this by creating a new variable
var itemViewControllers = [StackViewItemViewController]()
and then add each newly created viewController to it:
itemViewController.append(stackViewItemVC)
Related
I am trying to display a new image based on a user tapping the image view. I have added a UITapGestureRecognizer on top of the UIImageView which has been defined a "displayPhoto" and connected it as an outlet to the view controller.
#IBOutlet weak var displayPhoto: UIImageView!
#IBAction func changeImage(_ sender: UITapGestureRecognizer) {
displayPhoto.image = UIImage(named: "myimage")
}
The sent action is listed as follows:
sent actions
When I run the app and click on the image, nothing happens. I've even tried to make the first line of the IBAction function a fatal error but nothing happens. What am I missing?
Thanks in advance for any help.
The full view and connection
Tap Gesture Recognizer Window
Firstly you try; clean your project
command+option+shift+K
The first case cannot be empty
You should add a picture.
override func viewDidLoad() {
super.viewDidLoad()
displayPhoto.image = UIImage(named: "firsCase")
}
So I have a UItextfield and a UIButton I was wondering if there is a way to save the text after the button is pressed in an instance variable so that I could use it in my other class.
The thing I am trying to do is to have a user input some text in the textfield on screen 1 and then when the user taps the button I want to take him to screen 2 however in the class of that screen 2 I want to know what text user entered in order to display data accordingly.
Right now I just have an action function for the button and I access text inside it and save it to an instance variable but when I call it in my other class it is empty because I initialized it as empty. So can somebody please help me and tell me how to go about this.
Thanks!
Here is the code for first screen
var searchRecipe = ""
#IBAction func SearchButton(sender: UIButton) {
if let recipe = RecipeSearchBar.text {
searchRecipe = recipe
}
}
Here is the code for second screen. I have connected the button in first screen this screen so when user taps the button he gets here.
var recipeName:[String] = []
var imageURL:[String] = []
var timeInSeconds:[Float] = []
func apiCall()
{
//search recipe API call
var searchRecipe = ""
searchRecipe = RecipesViewController().searchRecipe
print (searchRecipe) //prints nothing
endpoint = "http://api.yummly.com/v1/api/recipes?_app_id=apiId&_app_key=apiKey&q=\(searchRecipe)" //this is where I want to use the searchRecipe text from class 1
}
Well personally I would do what follows (Based on my interpretation of your issue):
Please note that I take for granted you are implementing a view-controller-based navigation and you know what IBOutlets, IBActions & Segues are
In the first view controller create an IBOutlet property of
UITextField named RecipeSearchBar and connect it to the relative text
field.
In the second view controller create a variable value of type
string;
Change the storyboard segue identifier to "toSecondViewController"
Then in the first view controller create an IBAction to be called
when the UIButton is pressed.
In your case:
#IBAction func SearchButton(sender: UIButton) {
if let recipe = RecipeSearchBar.text {
searchRecipe = recipe
}
//If you are navigating into a new view view controller
//here you need to call self.presentViewController(...)
}
Inside this action, you are going to call self.presentViewController
to display your second view controller, but you have to do one last
very important step: pass the value of the UITextField to the instance
that will hold the second view controller
To achieve this, override prepareForSegue in your first view controller
and share the UITextField value. This method is triggered once you called self.presentViewController for further implementation.
//Did not tested the code but should just be ok
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
if (segue.identifier == "toSecondViewController")
{
//Create the instance
let secondViewController = segue.destinationViewController
//Set the value
secondViewController.value = searchRecipe;
}
}
You are now good to go.
Hope this helped, if so mark the question for others.
Bye
I have a UIViewController with a UILabel that needs to display either "lbs" or "kg". My app has a settings screen (another UIViewController) that is presented modally over the first view controller and the user can select either of the two units and save their preference. If the units are changed and the modal settings screen is dismissed, I of course want the label on the first view controller to be updated with the new units value (but without refreshing the whole view). I thought I knew how to make it work, but evidently I don't.
On my modal settings screen, I have a UISegmentedControl to allow the user to select units. Anytime it's changed, this function updates userDefaults:
func saveUnitsSelection() {
if unitsControl.selectedSegmentIndex == 0 {
UserDefaultsManager.sharedInstance.preferredUnits = Units.pounds.rawValue
} else {
UserDefaultsManager.sharedInstance.preferredUnits = Units.kilograms.rawValue
}
}
Then they would likely dismiss the settings screen. So, I added this to viewDidLoad in my first view controller:
override func viewDidLoad() {
super.viewDidLoad()
let preferredUnits = UserDefaultsManager.sharedInstance.preferredUnits
units.text = preferredUnits
}
That didn't work, so I moved it to viewWillAppear() and that didn't work either. I did some research and some caveman debugging and found out that neither of those functions is called after the view has been loaded/presented the first time. It seems that viewWillAppear will be called a second time if I'm working within a hierarchy of UITableViewControllers managed by a UINavigationController, but isn't called when I dismiss my modal UIViewController to reveal the UIViewController underneath it.
Edit 1:
Here's the view hierarchy I'm working with:
I'm kinda stuck at this point and not sure what to try next.
Edit 2:
The user can tap a 'Done' button in the navigation bar and when they do, the dismissSettings() function dismisses the Settings view:
class SettingsViewController: UITableViewController {
let preferredUnits = UserDefaultsManager.sharedInstance.preferredUnits
// some other variables set here
override func viewDidLoad() {
super.viewDidLoad()
self.navigationController?.navigationBar.topItem?.title = "Settings"
navigationItem.rightBarButtonItem = UIBarButtonItem(title: "Done", style: .Plain, target: self, action: #selector(self.dismissSettings(_:)))
if preferredUnits == Units.pounds.rawValue {
unitsControl.selectedSegmentIndex = 0
} else {
unitsControl.selectedSegmentIndex = 1
}
}
func dismissSettings(sender: AnyObject?) {
navigationController?.dismissViewControllerAnimated(true, completion: nil)
}
}
THE REAL PROBLEM
You misspelled viewWillAppear. You called it:
func viewWillAppear()
As far as Cocoa Touch is concerned, this is a random irrelevant function that hooks into nothing. You meant:
override func viewWillAppear(animated: Bool)
The full name of the first function is: "viewWillAppear"
The full name of the second function is: "viewWillAppear:animated"
Once you get used to this, the extreme method "overloading" that Cocoa Touch uses gets easier.
This is very different in other languages where you might at least get a warning.
The other lesson that everyone needs to learn when posting a question is: Include All Related Code!
Useful logging function I use instead of print or NSLog, to help find these things:
class Util {
static func log(message: String, sourceAbsolutePath: String = #file, line: Int = #line, function: String = #function, category: String = "General") {
let threadType = NSThread.currentThread().isMainThread ? "main" : "other"
let baseName = (NSURL(fileURLWithPath: sourceAbsolutePath).lastPathComponent! as NSString).stringByDeletingPathExtension ?? "UNKNOWN_FILE"
print("\(NSDate()) \(threadType) \(baseName) \(function)[\(line)]: \(message)")
}
}
[Remaining previous discussion removed as it was incorrect guesses]
The main ViewController is embedded in a UINavigationController subclass, and the VC has a subview that is loaded from a nib. The subview is called MenuView, and contains UIButtons that will link to other VCs.
To keep my main ViewController less unruly, I have put all these buttons into a subview that loads from a nib that animates the menu opening and closing.
However, I would like to present other view controllers from these, sometimes "Modally", sometimes "Show". What I have done seems to work, but I just want to know if this is alright, or if I have caused some unwanted effects that I'm unaware of (like a strong reference cycle that would cause a memory leak, or something). Or is there a better way to do this?
Some code:
In MenuView.swift
class MenuView: UIView {
var navigationController = CustomNavigationController()
func combinedInit(){
NSBundle.mainBundle().loadNibNamed("MenuViewXib", owner: self, options: nil)
addSubview(mainView)
mainView.frame = self.bounds
}
#IBAction func optionsAction(sender: AnyObject) {
self.navigationController.performSegueWithIdentifier("presentOptions", sender: self)
}
In ViewController.swift
menuView.navigationController = self.navigationController as! CustomNavigationController
Short answer: No, it is not alright to access a view controller from within some view in the hierarchy, because that would break all the MVC rules written.
UIView objects are meant to display UI components in the screen and are responsible for drawing and laying out their child views correctly. That's all there is. Nothing more, nothing less.
You should handle those kind of interactions between views and controllers always in the controller in which the view in question actually belong. If you need to send messages from a view to its view controller, you can make use of either the delegate approach or NSNotificationCenter class.
If I were in your shoes, I would use a delegate when view needs some information from its view controller. It is more understandable than using notification center as it makes it much easier to keep track of what's going on between. If the view controller needs some information from a view (in other words, the other way around), I'd go with the notification center.
protocol MenuViewDelegate: class {
func menuViewDidClick(menuView: MenuView)
}
class MenuView: UIView {
var weak delegate: MenuViewDelegate?
#IBAction func optionsAction(sender: AnyObject) {
delegate?.menuViewDidClick(self)
}
}
Let's look at what's going on at the view controller side:
class MenuViewController: UIViewController, MenuViewDelegate {
override func viewDidLoad() {
...
self.menuView.delegate = self
}
func menuViewDidClick(menuView: MenuView) {
navigationController?.performSegueWithIdentifier("presentOptions", sender: self)
}
}
For more information about communication patterns in iOS, you might want to take a look at this great article in order to comprehend how they work.
I created a navigation controller with a view controller inside, containing a label. This label should be changed, when the view controller is loaded on tapping a button.
class ViewController: UIViewController {
#IBOutlet weak var btnEmergency: UIButton!
override func viewWillAppear(animated: Bool) {
self.btnEmergency.backgroundColor = UIColor.redColor();
}
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func btnEmergencyTapped(sender: AnyObject) {
let emergencyViewController = storyboard?.instantiateViewControllerWithIdentifier("EmergencyViewController") as! EmergencyViewController
emergencyViewController.emergencyLabel?.text = "Notruf"
navigationController?.pushViewController(emergencyViewController, animated: true)
}
}
But the label text does not change when loaded. I am relatively new to SWIFT so I try to learn my ropes at the moment using optionals. So I guess the reason is, that the label is not yet instantiated when the view is being loaded on pressing the button. Therefore the default text is being shown and not the text I want to have appear on screen.
I am a little bit stuck at the moment, how to correctly change the label text, when this is an optional. So I guess I cannot expect the label to be there, when I call it. But how do I handle this correctly?
Instead of this, the correct way is to set a property of your emergencyViewController.
In your emergencyViewController viewDidLoad set your label text according to the property set previously.
Anything that you do between initialize of a viewController to viewDidLoad will not take effect.