There is similar question on Stack Overflow, but the problem there was different then mine, so I feel free to open this one.
I have iOS view controller with a UIDatePicker defined in storyboard.
I have defined(connected) IBOutlet in view controller code like this:
#IBOutlet weak var endTimeDatePicker: UIDatePicker!
At one point I set initial date like this:
endTimeDatePicker.date = state!.endTime;
or like this:
endTimeDatePicker.setDate(state!.endTime, animated: true);
and it shows correct date indicating that date picker is connected correctly.
But then, if I pick another date and try to get selected date with endTimeDatePicker.date it always returns the same - today's date, no matter what I pick.
Storyboard properties for date picker are:
Mode - Date and Time
Interval - 1 minute
Date - Current Date (but it's the same with custom, only returning defined custom date every time)
Is there something that I've missed to do?
I don't have for sure two different datePickers (like in potential duplicate Stack Overflow questions)
EDIT: looks like it only happens when Date Picker has set initial value from code.
EDIT: code that sets Date Picker:
private func reloadData (state : State?)
{
if (state != nil)
{
endTimeDatePicker.setDate(state!.endTime, animated: true);
backgroundImage.image = UIImage(named: state!.type.imageName)!;
}
else
{
let endDate = NSDate(timeIntervalSinceNow: 1800);
endTimeDatePicker.setDate(endDate, animated: true);
backgroundImage.image = UIImage(named: StateType.Active.imageName);
}
}
Code that tries to read selected date:
#IBAction func doneTapped(sender: AnyObject) {
let row: Int = self.stateTypePicker.selectedRowInComponent(0);
state = State (id: -1, type: stateTypes[row], startTime: NSDate(), endTime: self.endTimeDatePicker.date);
service.addState(state!) {
(responseDict) in
}
}
func reloadData is called in callback for http request. Could be thread lock problem maybe?
Your issue is related to the callback method reloadData from the NSURLSession. In here, you are updating the UIDatePicker in a background thread, but all UI updates have to be done on the main thread.
This is the reason why you are seeing todays date, when you are reading the date property of the UIDatePicker.
Related
I know there are a lot of answers out there about similar issues, but it seems all of them are don't fit to my problem. And I am new to Swift and my head is burning about all this stuff.
The task is very simple. I have a ViewController and a Class called "TimeIsTicking", which I defined in a separate Swift File. I did this, because I want to feed 5 ViewController (which are nested in TabBarController) with data from the Timer and they all have to run "synchronized".
The function fireTimer puts every second the value of 1 to the variable seconds.
In the ViewController is a Label and I want the Label to be updated every time when the timer puts a new value to seconds.
dayLabelText gets the data, here is everything fine, but from that point I'm stuck. Label Text isn't been updated.
I suspect, that there has to be a "loop" to reload the data for the Label and I thought the loop in fireTimer would be enough but I was obviously wrong.
I tried the "Observer Thing" and the "Dispatchqueue Thing" but I didn't play well ((obviously).
Help would be much appreciated.
Here is the code of the timer class:
import Foundation
import UIKit
class TimeIsTicking {
var seconds: Int = 0
static let timeFlow = TimeIsTicking()
func fireTimer() {
let finance = FinanceVC()
Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
self.seconds += 1
finance.dayLabelText = "\(self.seconds)"
print("Seconds: ", self.seconds)
print("LabelText: ", finance.dayLabelText)
}
}
}
And here is the code of the VieWController:
import UIKit
class FinanceVC: UIViewController {
#IBOutlet weak var dayLabel: UILabel!
var dayLabelText = String(TimeIsTicking.timeFlow.seconds)
override func viewDidLoad() {
super.viewDidLoad()
dayLabel.text = dayLabelText
TimeIsTicking.timeFlow.fireTimer()
}
// Do any additional setup after loading the view.
}
I see a few issues:
The finance object goes out of scope when fireTimer() returns. It will be deallocated then. The timer will be setting a label text on a no longer existing view controller.
Instantiating a UIViewController with FinanceVC() doesn't display it on screen. After instantiating you need to explicitly show. You can do this for example by calling present(_:animated:completion:) from a parent view controller.
The timer updates dayLabelText which does not update dayLabel.text
Might be good to follow a basic YT tutorial on how to display a view controller.
Good luck, you'll get it soon enough!
I am having this strange issue in UIDatePicker mode .countdownTimer
When I add constraints of up/down/left/right to the datePicker view, the callback is not registered for the first time. However, if I add only Alignment constraints, the callback works everytime. Maybe its a bug. Any idea why isn't it working?
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var datePicker: UIDatePicker!
override func viewDidLoad() {
super.viewDidLoad()
datePicker.datePickerMode = .countDownTimer
datePicker.addTarget(self, action: #selector(datePickerValueChanged(_:)), for: .valueChanged)
}
#objc func datePickerValueChanged(_ sender: UIDatePicker){
print("Selected value \(sender.countDownDuration)")
}
}
OK, it's a long-known bug in iOS, since iOS 7 or so.
You can work-around in your case if you put the following somewhere into viewDidLoad:
DispatchQueue.main.async {
self.datePicker.countDownDuration = self.datePicker.countDownDuration
}
Seems nasty, and is nasty.
The workaround of setting the countDownDuration didn't work for me. Instead the only way I managed to solve this is to replace the UIDatePicker with a UIPickerView and populate it myself with 4 components: hours, "hour(s)" label, mins, "min(s)" label.
The hours are 0-23
The hours label is a single row component, which
gets reloaded when the hours are changed so that it switches to
"hour" when it's 1 hour
The mins are 0-59
The mins label is the same
as the hours label
I was able to fix this issue in SwiftUI (using a "UIDatePicker" created with "UIViewRepresentable") by appending an "onAppear" to the picker and inside the closure updating the state variable used for tracking the duration to any value that is not the default value. This forces a programmatic update on the first render which then allows the picker to work correctly on the first spin.
I'm trying to replicate the default Clock app found on the iPhone in order to learn swift better and get used to different parts of iOS Development.
I'm currently working on the timer section of the app.
I have a DatePicker to get the date and I'm assigning the countdownDuration property to a TimeInterval when the timer starts.
This is giving me a random value each time however (always seems to be around 80.0-120.0)
I fully understand I might have the concept of TimeIntervals wrong but from what I've read online and in the Developer Documentation, I have the concept right?
Here is the code I'm using to run the timer:
#IBOutlet weak var datePicker:UIDatePicker!
var IsTimerRunning:Bool = false;
var TimerDuration:TimeInterval = 0;
var timer:Timer?;
//Called every second when timer is running
#objc func onTimerFires() {
TimerDuration = TimerDuration - 1.0;
print (TimerDuration);
if (TimerDuration <= 0.0) {
EndTimer();
}
}
func EndTimer() {
timer?.invalidate();
IsTimerRunning = false;
}
//Start button pressed
#IBAction func StartButtonPressed() {
if (IsTimerRunning == false) {
TimerDuration = datePicker.countDownDuration;
timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(onTimerFires), userInfo: nil, repeats: true)
IsTimerRunning = true;
}
}
A couple of considerations:
Make sure your date picker has a Mode of countDownTimer. As the documentation says:
If the mode of the date picker is not UIDatePicker.Mode.countDownTimer, this value [countDownDuration] is undefined...
If you added this on IB, you may want to set "date" property to "Custom". As the documentation warns us:
Note
When you use Interface Builder to set the Mode attribute to Count Down Timer and specify a value for the timer attribute, your date picker may not respect the Timer attribute value when you build and run your project. If this happens, return to the Attributes inspector for the date picker, select Custom in the Date pop-up menu (you can ignore the associated value), and rebuild your project.
I notice very strange countDownDuration values until I selected "custom" for the "Date" pop-up menu in IB.
Let's say that I have a UIDatePicker and the mode is set to .date.
I want the following behaviour:
For example, March has 30 days. If I scroll below the 30th day, I want the month to be automatically incremented to April and so on.
Is there a property that does just that? I couldn't find one.
Thanks.
I don't think there's any way to do what you want with a normal UIDatePicker. You could attach an action to the valueChanged event, but that doesn't get called until the date picker stops moving.
You could probably create a custom date picker using a standard UIPickerView. You could use the data source methods to figure out when the "wheels" are turned, call selectedRow(inComponent:) to figure out which values are selected for each wheel, and then call selectRow(_:inComponent:animated) to switch the month if the user scrolls the day past the end of the month.
How to advance other fields in datePicker automatically?
The best way to do this is using the Target-Action design pattern. Basically, when a user chooses a new date (action), the view (a target) does something.
Here's some code that changes the day value to 1 if it's set to 0:
override func viewDidLoad() {
...
let datePicker = UIDatePicker()
datePicker.datePickerMode = .date
datePicker.addTarget(self, action: #selector(doStuff(sender:)), for: UIControlEvents.valueChanged)
view.addSubview(datePicker)
...
}
#IBAction func doStuff(sender: UIDatePicker) {
let calendar = Calendar.current
let components = calendar.dateComponents([.day], from: sender.date)
if components.day == 0 {
// Using Calendar.current automatically takes care of Time Zones for us.
if let date = calendar.date(byAdding: .day, value: 1, to: sender.date) {
sender.setDate(date, animated: true)
}
}
}
Note: This example is in Swift 4.
No, there is no property that does this that I am aware of.
I am trying to build a zodiac sign app for class. I am using a UIDatePicker and an UIImageView to display the image once the user picks a date (date range, say if the date of birth is between a certain date). The zodiac will be revealed in text and also the image appears. So far I have my user interface and all the images ready, but I am not sure how to go with the main code for it to function properly.
var zodiac = ["Aqurius", "Pisces", ...]
override func viewDidLoad() {
zodiacSign.text = zodiac[0]
}
Add an #IBAction by ctrl-dragging from your UIDatePicker in Interface Builder to your view controller.
#IBAction func datePickerChanged(sender: AnyObject) {
let date = datePicker.date
// configure your labels and images according to date
}