I'm using shouldChangeCharactersInRange as a way of using on-the-fly type search.
However I'm having a problem, shouldChangeCharactersInRange gets called before the text field actually updates:
In Objective C, I solved this using using below:
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSString * searchStr = [textField.text stringByReplacingCharactersInRange:range withString:string];
return YES;
}
However, I've tried writing this in Swift:
func textField(textField: UITextField!, shouldChangeCharactersInRange range: NSRange, replacementString string: String!) -> Bool {
let txtAfterUpdate:NSString = self.projectSearchTxtFld.text as NSString
txtAfterUpdate.stringByReplacingCharactersInRange(range, withString: string)
self.callMyMethod(txtAfterUpdate)
return true
}
The method still gets called before I get a value?
Swift 4, Swift 5
This method doesn't use NSString
// MARK: - UITextFieldDelegate
extension MyViewController: UITextFieldDelegate {
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
if let text = textField.text,
let textRange = Range(range, in: text) {
let updatedText = text.replacingCharacters(in: textRange,
with: string)
myvalidator(text: updatedText)
}
return true
}
}
Note. Be careful when you use a secured text field.
stringByReplacingCharactersInRange return a new string, so how about:
func textField(textField: UITextField!, shouldChangeCharactersInRange range: NSRange, replacementString string: String!) -> Bool {
if let text = textField.text as NSString? {
let txtAfterUpdate = text.replacingCharacters(in: range, with: string)
self.callMyMethod(txtAfterUpdate)
}
return true
}
Swift 3 & 4
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let textFieldText: NSString = (textField.text ?? "") as NSString
let txtAfterUpdate = textFieldText.replacingCharacters(in: range, with: string)
callMyMethod(txtAfterUpdate)
return true
}
func textFieldShouldClear(_ textField: UITextField) -> Bool {
callMyMethod("")
return true
}
Swift 2.2
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let textFieldText: NSString = textField.text ?? ""
let txtAfterUpdate = textFieldText.stringByReplacingCharactersInRange(range, withString: string)
callMyMethod(txtAfterUpdate)
return true
}
func textFieldShouldClear(textField: UITextField) -> Bool {
callMyMethod("")
return true
}
Though the textField.text property is an optional, it cannot be set to nil. Setting it to nil is changed to empty string within UITextField. In the code above, that is why textFieldText is set to empty string if textField.text is nil (via the nil coalescing operator ??).
Implementing textFieldShouldClear(_:) handles the case where the text field's clear button is visible and tapped.
In Swift 3 it would look like this:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let text: NSString = (textField.text ?? "") as NSString
let resultString = text.replacingCharacters(in: range, with: string)
return true
}
shouldChangeCharactersIn is called on every key press.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
// get the current text, or use an empty string if that failed
let currentText = textField.text ?? ""
// attempt to read the range they are trying to change, or exit if we can't
guard let stringRange = Range(range, in: currentText) else { return false }
// add their new text to the existing text
let updatedText = currentText.replacingCharacters(in: stringRange, with: string)
// make sure the result is under 16 characters
return updatedText.count <= 16
}
shouldChangeCharactersInRange
func textField(textField: UITextField!, shouldChangeCharactersInRange range: NSRange, replacementString string: String!) -> Bool { }
This function is called when changes are made but UI is not updated and waiting for your choice
Take a look at returned bool value
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
If you return true - it means that iOS accept changes(text, caret...)
If you return false - it means that you are responsible for all this stuff
Swift 3
If you want to pre-process the characters the user typed or pasted, the following solution workes like a charm
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let strippedString = <change replacements string so it fits your requirement - strip, trim, etc>
// replace current content with stripped content
if let replaceStart = textField.position(from: textField.beginningOfDocument, offset: range.location),
let replaceEnd = textField.position(from: replaceStart, offset: range.length),
let textRange = textField.textRange(from: replaceStart, to: replaceEnd) {
textField.replace(textRange, withText: strippedString)
}
return false
}
Find it here: https://gist.github.com/Blackjacx/2198d86442ec9b9b05c0801f4e392047
This is essentially #Vyacheslav's answer independently arrived at for my own use case, just in case the stylistic approach resonates :-)
func textField(_ textField: UITextField, shouldChangeCharactersIn nsRange: NSRange, replacementString: String) -> Bool {
let range = Range(nsRange, in: textField.text!)!
let textWouldBecome = textField.text!.replacingCharacters(in: range, with: replacementString)
if textWouldBecome != eventModel.title {
self.navigationItem.setHidesBackButton(true, animated: true)
} else {
self.navigationItem.setHidesBackButton(false, animated: true)
}
return true
}
Replace eventModel.title with whatever you're checking for the change against obviously.
To get the exact text in the my UITextField component in Swift 3.0 I used:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let enteredTxt = textField.text! + string
doSomethingWithTxt(enteredTxt) //some custom method
}
Related
I'm trying to pass the value in my textfield to another view using delegates. This is how I tried to achieve that..
In the 2nd view from where the value is to be passed to main view, this is what I have written..
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if let _ = raDelegate {
raDelegate?.durationChanged(hrs: string)
}
return true
}
And in the first view, this is what I have...
func durationChanged(hrs: String) {
myView.durationTextField.text = hrs
}
Now the issue is that if I type in say "5" in the textfield, in the durationChanged function, on applying breakpoint, I get the value in hrs as "5" itself. But when I remove the breakpoint and run, then what gets finally printed to myView.durationTextField.text is 55. Also if I print "7" after that, the "55" gets replaced by "77". While ideally what I should have got was "57".
you use it wrongly.
string on shouldChangeCharactersIn function isn't the value of textField.
for example:
1. textField.text = ""
2. input 5 -> range is (0,0), string is 5, textField.text = "" (The textField.text isn't changed yet, it depends on return value of delegate function, if true it'll replace the textField.text with in range with string)
3. input 7 -> range is (1,0), string is 7, textField.text = "5"
4. input backspace -> range is (2, 1), string is "", textField = "57"
After 4, your textField.text = "5"
so you can revise your code:
let stringAfterChanged = ((textField.text ?? "") as NSString).replacingCharacters(in: range, with: string)
raDelegate?.durationChanged(hrs: stringAfterChanged)
You used shouldChangeCharactersIn wrongly. update your code with your controller extension
extension YourController: UITextFieldDelegate {
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
if let text = textField.text,
let textRange = Range(range, in: text) {
let updatedText = text.replacingCharacters(in: textRange,
with: string)
raDelegate?.durationChanged(hrs: updatedText)
}
return true
}
}
Or try this workaround
extension YourController: UITextFieldDelegate {
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
let previousText:NSString = textField.text! as NSString
let updatedText = previousText.replacingCharacters(in: range, with: string)
raDelegate?.durationChanged(hrs: updatedText)
return true
}
In iOS 13, when implementing shouldChangeCharactersIn via the UITextfieldDelegate, the application crashes when using the swiping keyboard.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if let text = textField.text as NSString? {
let txtAfterUpdate = text.replacingCharacters(in: range, with: string)
textField.text = txtAfterUpdate
}
return false
}
Is this an Apple bug?
I was able to reproduce this - if you mutate the state of the text on a UITextField during swipe entry - and only during swipe entry, it'll attempt to reinsert the swiped content (even if you return false), which retriggers your delegate event, which kicks off the recursive cycle.
It's a bit of a hack but you could catch it with something like
private var lastEntry: String?
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if string.count > 1 && string == lastEntry { // implies we're swiping or pasting
print("Caught unwanted recursion")
return
}
lastEntry = string
if let text = textField.text as NSString? {
let txtAfterUpdate = text.replacingCharacters(in: range, with: string)
textField.text = txtAfterUpdate
}
return false
}
It'll stop users from pasting/swiping the same thing twice in a row, but at least it'll let them swipe while Apple fixes their problem.
I used UIPasteboard to identify when the user is pasting and then leave the text as the user entered using the swipe like this:
public func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
//check if the user used swipe keyboard
if string.count > 1 && string != UIPasteboard.general.string ?? "" {
return true
}
//do the text treatment
return false
}
I also realized that the TextField only accepts static strings when using swipe keyboard.
Hope it Helps.
Before setting text you can reset delegate and after set it to self again.
But this solution has one problem if textfield is empty - text will be doubled.
Му code example:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let currentText: String = textField.text ?? ""
if #available(iOS 13, *) {
textField.delegate = nil
let resultText = editedText
textField.text = resultText
if currentText.isEmpty, textField.text != resultText {
textField.text = resultText
}
textField.delegate = self
} else {
textField.text = input.result
}
return false
}
How do we disallow empty input on textField?
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let oldText = textField.text!
let stringRange = Range(range, in:oldText)!
let newText = oldText.replacingCharacters(in: stringRange, with: string)
doneBarButton.isEnabled = !newText.isEmpty
return true
}
Is there other ways? or using other textField delegate methods to do this?
Yes, this is basically how you do it.
Alternatively, if all you want to know if the field is empty or not, just figure out the length of the result:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let length = (textField.text?.count ?? 0) + string.count - range.length
doneBarButton.isEnabled = length > 0
return true
}
You may also want to set enablesReturnKeyAutomatically for the text field to true, so that the keyboard doesn’t enable the “return” key unless there is text in the field.
I am looking to cap the amount of characters a user can type into a textfield at 14. Here is the code that I have found documentation on.
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let currentCharacterCount = userNameTextField.text?.characters.count ?? 0
if (range.length + range.location > currentCharacterCount){
return false
}
let newLength = currentCharacterCount + string.characters.count - range.length
return newLength <= 14
}
but I do not feel that I am implementing this correctly. I have set
userNameTextField.delegate = self
in the viewDidLoad, and I am conforming to the UITextFieldDelegate protocol.
You state you are using Swift 3. The signature of many methods changed in Swift 3. You need to use:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
}
Not the old signature posted in your question.
If it's still not being called, then you never set the text field's delegate property.
Try this instead:
func textField(textField: UITextField!, shouldChangeCharactersInRange range: NSRange, replacementString string: String!) -> Bool {
let currentString: NSString = (textField.text ?? "") as NSString
let newString = currentString.replacingCharacters(in: range, with: string)
return newString.characters.count <= 14
}
Try this for swift 3:
let limit=4;
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard let text = txtSMSCode.text else { return true }
let newLength = text.characters.count + string.characters.count - range.length
return newLength <= limit
}
I am attempting to regulate the input of a UITextfield in real time, meaning as a user is typing. I have this character set that i need to compare to the input string, and while editing if an unwarranted character is typed in, I want to relay an alert. Here is my character set :
let acceptedChars = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_")
now how do i capture a specific textfield in real time and track its input?
Try this:
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
let invalidCharacters = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_").invertedSet
if let range = string.rangeOfCharacterFromSet(invalidCharacters, options: nil, range:Range<String.Index>(start: string.startIndex, end: string.endIndex)) {
return false
}
return true
}
You can register your textField for value change event like this
textfield.addTarget(self, action:"textFieldDidChange", forControlEvents:UIControlEvents.EditingChanged)
func textFieldDidChange(){
// put your code
}
It will work for each chracter you have been typed in real time
var strings: NSString?
class ViewController: UIViewController,UITextFieldDelegate //set your textfield delegate
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{ if(textField .isEqual(your textfield))
{
strings=string;
let acceptedChars = NSCharacterSet(charactersInString: "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_").invertedSet;
if (strings!.rangeOfCharacterFromSet(acceptedChars.invertedSet).location != NSNotFound)
{
return true;
}
else
{
return false;
}
}
else
{
return true;
}
}
use below method
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
if textField.isEqual(<textField whose value to be copied>)
{
<TextField to be updated>.text = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)
}
return true
}
An Easy Delegate method and really more efficient is:
func textFieldDidChangeSelection(_ textField: UITextField) {
print(textField.text)
}