I want to know if there is a way to know the value of textfield before the value is changed to the new value.
For example:
If the text field had a value "a" and the user entered "b", so the editing changed event is fired. When I try to fetch the value of the text field in the debugger it will display "ab". Is there a way that I can get "a" before "b" was written?
Here is a piece of code where I am trying to fetch the value:
#IBAction func commentEditingChanged(sender: AnyObject) {
if(!((sender as? UITextField)!.text!.isEmpty)){
counter++
}
else
{
counter--
}
}
In this case I want to know if the text was empty before the user entered text because I don't want the counter increments every time the user enters a character. I want to increment once the user entered any text.
And please don't propose to use delegate function textField:shouldChangeCharactersInRange:replacementString because my question is about this IBAction method.
If there is no way to do that using this IBAction Method, is there is any other IBAction method that can achieve what i want?
Related
I have Swift object with about 20 Properties. In the app, there is a screen to get the user input and create the above swift object from the user entered value. Right now, if the user clicks the back button, all the user entered data will lose. So I want to alert the user to save the details if he/she has made any changes. How do we identify if the user has made any changes to the properties. Is it possible to use KVO in this case as we have too many properties?
What you need is a data model to hold the information in that particular screen, and then compare it with the original data when leaving the screen.
For the sake of simplicity, let's assume your screen has 2 text fields. One holds a name and another the age of a person.
struct Person: Equatable {
var name: String
var age: Int
}
When you first open this screen, the model will have the default values. Create a copy of this model and whenever the user makes any changes to the values on the screen, update the copy.
class YourViewController: UIViewController {
// Populate these 2 values when creating your view controller
var person: Person!
var personCopy: Person!
.
.
.
// You need to add this target to your text fields
#objc func textFieldDidChange(_ textField: UITextField) {
switch textField {
case personTextField:
personCopy.name = personTextField.text!
case ageTextField:
personCopy.age = Int(ageTextField.text!)!
default:
// Handle other text fields here or write separate cases for them
}
func dismissView() {
if person == personCopy {
// Dismiss your view
} else {
// Show alert
}
}
}
If the user presses the back button, all you need to do is compare these 2 models and check if they are the same. If they are the same, you can go back, if not, prompt an alert asking the user to save changes or discard.
I think KVO would be overkill here. Use KVO only for distant objects in your app.
Here you have the UITextFields in your viewController and you must have reference to the user object anyway.
Easier is: On the back button press you would check all text properties of your UITextField objects to the (existing) values of your user object. If one of them has changed then present the alert.
I have 100 UITextField boxes in storyBoard which are stored in an array called boxArray.
I also have another array called importantIndexes, which stores important indexes of boxArray.
(Bear with me on this on this next paragraph)
When a user taps on a specific UITextField box in boxArray who's index matches a value in the importantIndexes array. I then want to return the index of importantIndexes array which value is the index of the boxArray first responder.
This is the function that gets called when one of the specific UITextField are tapped:
#objc func myNotWorkingFunction(textField: UITextField) {
for i in 0...99 {
if (boxArray[i]?.isFirstResponder)! {
let index = boxArray.index(of: boxArray[i])
print(index)
}
}
}
I'm running into two problems. The first is that the print function is returning "Optional(Index)". I just want the int value Index but it's printing it like this example: Optional(14).
My second problem is that this seems to print the index of first responder of whatever was the first responder before it was changed to the new one. Let's say the user was at 11th boxArray UITextField, then taps on the 55th, the print returns "Optional(11)" instead of just "55" which is what I want.
I can't use textFieldDidEndEditing(:_) here, which would probably work fine. I have to stick with the tapping functionality. Any ideas?
First problem is solved by unwrapping
if let index = boxArray.index(of: boxArray[i]) {
print(index)
}
Second problem 'may' be that you need to call this when your objc function is called.
declare:
var currentTextField: UITextField?
In your function:
currentTextField?.resignFirstResponder()
currentTextField = textField
textField.becomesFirstResponder()
I have a UIViewController with several UITextFields. When tap one text field, it should present the barcode scanning view controller. Once the scanning is completed, my barcode scanning viewcontroller is disappearing (used "dismissViewcontroller") and the scanned value should entered into the text field I tapped. This is working fine. I have set the delegate for each text field like this.
[field addTarget:metrixUIViewControllerIn action:#selector(executeScriptOnTextFieldChange:) forControlEvents:UIControlEventEditingChanged];
The problem is this :
Lets say I have set an alert to display inside this executeScriptOnTextFieldChange method. Once I tapped on the 1st text field, then the barcode scanner comes. Once I scanned barcode scanner closes and set the value for the first text field and fire the alert.Thats ok. But then if scanned by tapping the 2nd textfield and the string will set to that textfield and fire the alert related to 2nd textfield also fire the alert related to first textfield as well. I want to stop happening this. Is there any way to disable the delegate for one textfield? This happens because I am refreshing the view in the viewDidAppear. But I have to do that as well. Please help me.
UIControlEventEditingChanged for a textField can fire at many different events that are not even directly related to that textField, but related inderectly.
For instance, when your ViewController is presenting the barcodeScanner it may trigger a "resignFirstResponder" event on the textField. Also when the 2nd textField is tapped, cause the 2nd becomes first responder and the 1st suffers a "resignFirstResponder".
I suggest trying to use a UITapGestureRecognizer in your textField instead. Example:
Swift 4
#IBOutlet weak var textField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
self.textField.tag = 1
self.textField.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(fireTextField(_:))))
}
#objc func fireTextField(_ sender: UIGestureRecognizer){
let view = sender.view
guard view != nil else{
//Do nothing
return
}
let condition = view!.tag == 1
if condition{
//or do whatever other stuff you need
self.textField.becomeFirstResponder()
}else{
//Whatever for other textFields
}
}
This way, you could use the "tag" attribute to determine which textField is firing and so adjust "condition". You could also filter the flow with a switch using the "tag".
Not sure if any of this will really help as I would need more info about the flow you need to accomplish. Hope it does help!
Evening, in my app I have several UITextfield. Each one has to confirm to different limitations.
For example, I have a date Field, zipCode Field, SSN Field etc.
From the Apple Documentation I found:
Assign a delegate object to handle important tasks, such as:
Determining whether the user should be allowed to edit the text field’s contents.
Validating the text entered by the user.
Responding to taps in the keyboard’s return button.
Forwarding the user-entered text to other parts of your app.
Store a reference to the text field in one of your controller objects.
So I'm pretty sure I have to use delegates and func textFieldDidEndEditing(_:).
The only way that came to my mind is to use a switch statement inside the func textFieldDidEndEditing(_:) to confirm the delegate to the difference limitation.
Is there a better, safer and faster pattern to face this problem?
You can set unique tag to your every text field and can compare in textFieldDidEndEditing or you can take IBOutlet of every textField and can compare it in textFieldDidEndEditing like,
func textFieldDidEndEditing(textField: UITextField) {
// By tag
if textField.tag == 100 {
}
// OR
//by outlet
if textField == self.myTextField {
}
}
You are right, you will have to check the textfield, either you can check tags assigned for different text fields using switch statement like you said,
or you can compare textfields itself,
if textfield1,textfield2 are outlets to two text fields, you can compare as following,
func textFieldDidEndEditing(textField: UITextField)
{
if textField == textfield1
{
}
else if textField == textfield2
{
}
}
you can create enum for validation
enum Type {
case zipcode
case number
}
then you can create a method for validation like this :
func isValidate(text: String, type: Type) -> Bool {
switch type {
case .zipcode:
...
}
}
this method can be in Util class. this is best practice. because your logic is encapsulate from out .
If you need more control over the text which is committed to the text field or if you want to provide feedback while the text field is being edited, you should implement a different delegate instead:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
// Build and check the new text value. Accept or reject the change.
}
In the delegate, you can build the new text value. Validate it, apply constraints, decide on which feedback the user should receive ("Your password must be at least eight characters long", "This is not a valid IBAN"), accept or reject the change (i.e. return false).
Keep in mind, that the delegate is not called if you assign the text property manually. Moreover, this delegate is called when text is pasted into or deleted from the text field, which can make matters much more complicated depending on what you do.
I am trying to understand delegate methods in general, and specifically how to dismiss a UIDatePicker that popovers from a text field.
According to the documentation, textFeildShouldBeginEditing returns true 'if an editing session should be initiated; otherwise, false to disallow editing.'
Why would I then tell the app to resignFirstResponder, which is meant to hide the keyboard / date picker (as in several examples on stackoverflow and noobie tutorials)?
What I don't understand is: if it should begin editing, why then hide the input devise? Obviously, I am misunderstanding one or both concepts.
func resign() {
dobTextField.resignFirstResponder()
nameTextField.resignFirstResponder()
println("resign gets printed, but the date picker is still visible!?!")
}
func textFieldShouldBeginEditing(textField: UITextField) -> Bool {
if (textField === dobTextField) {
resign() // but should begin editing, oder?!?
}
In the examples you cite, the textField is being used to display a date. When the user selects this field, the app designers want the UIDatePicker to be displayed instead of the keyboard. Hence they call resignFirstResponder to hide the keyboard. At the same time, they display the date picker.
ResignFirstResponder will not hide the date picker, so the "input device" (for this field) will still be available.
Also, note that in one case the developer has used textFieldShouldBeginEditing, and returns false because they are providing the date picker. In the other case the developer uses textFieldDidBeginEditing (which has no return value).
you should resign only the textfield not affected:
func textFieldShouldBeginEditing(textField: UITextField) -> Bool {
if textField == dobTextField {
nameTextField.resignFirstResponder()
} else if textField == nameTextField {
dobTextField.resignFirstResponder()
}
return true
}
this way you are resiging first responder only on the textfields that should not currently be edited. this helps if for some reason you accidentally have 2 textfields (or more) assigned first responder causing conflicts with multiple keyboards/datepickers and such.