How do I make a label in my ViewController have a diffrent string of text each time the view crontroller is shown? Thanks! I'm using Swift 3
Assuming you know how to add UILabel to your ViewController, here is quick sample how to pick random text on start:
class ViewController: UIViewController {
let allTexts = ["Hey", "Hi", "Hello"]
#IBOutlet weak var label: UILabel! //get UILabel from storyboard
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.label.text = self.allTexts[Int(arc4random_uniform(UInt32(self.allTexts.count)))]
}
}
Adding this code to viewWillAppear will change your text anytime ViewController is about to appear - which means if you cover it with another ViewController (let's say popup) and then hide popup - it will change text.
If your prefer to just do it one time - when UIViewController is created put the same code inside viewDidLoad method.
Related
I need to add delegate to textfields; my understanding is it can be done two ways:
we go to file and viewController.swift and under class, after UIviewcontroller we add comma and then type UITextFieldDelegate .
and then u under viewDidLoad we add method and function
when on storyboard we click and drag textfield to small icon on top of view that says view controller and pick delegate
Do they both work the same? or there is difference if we do one way or the other?
and what you do if you have more than one textfields, I have 10 textfields and have 7 functions and buttons, I need to do this so I can disable button if my textfield is empty for that button.
There is no difference, as far as I know. Choose what you like more.
In first case you also need to make #IBOutlet for your UITextField(click and drag UITextField from UIStoryboard to your UIViewController code) and after that make UIViewController delegate of UITextField
For example:
import UIKit
class MyViewController: UIViewController, UITextFieldDelegate
{
#IBOutlet weak var myTextField: UITextField!
override func viewDidLoad()
{
super.viewDidLoad()
myTextField.delegate = self
}
}
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)
I have a UIButton inside my cell together with an image and a text label. I manage to change the image and label programatically, but the UIButton does not seem to respond to anything except isHidden.
This is my code, the button that is not changing is followButton:
import UIKit
class ProfileTableCell: UITableViewCell {
#IBOutlet weak var name: UILabel!
#IBOutlet weak var profileImage: UIImageView!
#IBOutlet weak var followButton: UIButton!
override func awakeFromNib() {
super.awakeFromNib()
self.profileImage.layer.borderWidth = 0.0;
self.profileImage.layer.cornerRadius = self.profileImage.frame.size.width/2;
self.profileImage.clipsToBounds = true
self.profileImage.image = UIImage(named: "belt")
self.name.text = "Bar Refaeli"
self.followButton.layer.borderColor = UIColor.black.cgColor
self.followButton.layer.borderWidth = 3.0;
self.followButton.layer.cornerRadius = self.frame.size.width/4
self.followButton.backgroundColor = UIColor.black
}
func setCell(image: UIImage, name: String){
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
The profileImage and name outlets change the appearance fine, like mentioned above.
I also tried to remove the button and bring it back in, clean xcode project, remove the outlet reference and connecting it again. Pretty frustrated by now.
I also tried to change the background color of the button through the storyboard, just for testing, and it does not change it! what does change is the titleLabel and the text color.
awakeFromNib()- Prepares the receiver for service after it has been loaded from an Interface Builder archive, or nib file.
Given that, move your code to a view initiating method like viewDidLoad or viewDidAppear(_:)
Child objects that are attributes like textLabels act differently than child view objects.
Eventually I actually solved this by tossing the table view to the garbage and implementing the same needs using a collection view. there was no problem there..
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.
I am using swift and want a UITextView to be at the top when the view launches. At the moment when I launch the app the UITextView is scrolled to the end. I have tried looking online and think scrollRangeToVisible might work but do not know how to use it in swift.
import UIKit
class ThirdViewController: UIViewController {
#IBOutlet weak var FunFact: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
FunFact.scrollRangeToVisible(0, 0)
// Do any additional setup after loading the view.
}
}
Add this to your ViewController:
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
textView.layoutIfNeeded()
textView.contentOffset = CGPoint.zero
}
This scrolls the UITextView to the top. Since it only knows its size, when it is layouted, "layoutIfNeeded" is needed after you changed the text (i changed it in viewDidLoad).
Try this:
var zeroOffset = CGPoint.zeroPoint
FunFact.contentOffset(zeroOffset)
This should bring the offset to 0 (the offset is an indication of how far the current position is from the initial one)