i have a text field delegate method my use cases are :-
if (.) dot is not there limit input to two characters because 100% should not be discount.
if user input is 1.99 how can update the delegate method that it should take two numbers after (.)
same if input is 12.99 how can update the delegate method that it should take two numbers after (.)
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard !string.isEmpty else {
return true
}
// maximum limit of input 2 as 100% should not be discount.
if !textField.text!.contains(".") {
let maxLength = 2
let currentString: NSString = (textField.text ?? "") as NSString
let newString: NSString = currentString.replacingCharacters(in: range, with: string) as NSString
return newString.length <= maxLength
} else {
// if there is (.)
let maxLength = 3
let currentString: NSString = (textField.text ?? "") as NSString
let newString: NSString = currentString.replacingCharacters(in: range, with: string) as NSString
return newString.length <= maxLength
}
}
CodePudding user response：
One option is to keep track of number of digits before and after a decimal point and decide if you have reached your threshold.
There is nothing wrong with your answer, but here is an alternative option if you like. You could use regex as sometimes keeping track of multiple bools, counts, variables might have some edge cases.
My REGEX skills are not too strong but here is a 
Update based on Omar's comment:
one question if I press .5 at starting, textfield should show 0.5 how to achieve this using same regex
I think rather than handling this using regex, we could handle this as an edge case as this would seem easier to me.
We check if the first character entered is a decimal and add the 0 then.
Here is what I would do:
extension TextHighlightVC: UITextFieldDelegate {
func textField(_ textField: UITextField,
shouldChangeCharactersIn range: NSRange,
replacementString string: String) -> Bool {
guard let text = textField.text else { return false }
// Check if the first character entered is a decimal
if text.count == 0 && string == "." {
// Add 0 to the text field
textField.text = "0"
return true
}
return isValidDecimal(text string)
}
}
CodePudding user response：
this is the answer
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
guard !string.isEmpty else {
return true
}
let newText = (textField.text! as NSString).replacingCharacters(in: range, with: string) as String
if let num = Double(newText), num >= -1 && num <= 100 {
return true
} else {
return false
}
}