I want the user to only enter numeric values in a UITextField
. On iPhone we can show the numeric keyboard, but on iPad the user can switch to any keyboard.
The following solution has two benefits:
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
return NumberFormatter().numberFrom(text: (textField.text ?? "") + string) != nil
}
func isValidNumber(str:String) -> Bool{
if str.isEmpty {
return false
}
let newChar = NSCharacterSet(charactersInString: str)
let boolValid = NSCharacterSet.decimalDigitCharacterSet().isSupersetOfSet(newChar)
if boolValid{
return true
}else{
let lst = str.componentsSeparatedByString(".")
let newStr = lst.joinWithSeparator("")
let currentChar = NSCharacterSet(charactersInString: newStr)
if lst.count == 2 && !lst.contains("") && NSCharacterSet.decimalDigitCharacterSet().isSupersetOfSet(currentChar){
return true
}
return false
}
}
Put this function in your "Submit" or "Save" method if there is one.
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
// return true if the replacementString only contains numeric characters
let digits = NSCharacterSet.decimalDigitCharacterSet()
for c in string {
if !digits.characterIsMember(c) {
return false
}
}
return true
}
This solution will work even if the user switches keyboards or tries to paste a non-numeric string into the text field.
Make sure to set the delegate
property of the appropriate text field.
Accept decimal values in text fields with single (.)dot in Swift 3
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let inverseSet = NSCharacterSet(charactersIn:"0123456789").inverted
let components = string.components(separatedBy: inverseSet)
let filtered = components.joined(separator: "")
if filtered == string {
return true
} else {
if string == "." {
let countdots = textField.text!.components(separatedBy:".").count - 1
if countdots == 0 {
return true
}else{
if countdots > 0 && string == "." {
return false
} else {
return true
}
}
}else{
return false
}
}
}
Tested in swift 3.0
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
let numberOnly = NSCharacterSet.init(charactersIn: "0123456789")
let stringFromTextField = NSCharacterSet.init(charactersIn: string)
let strValid = numberOnly.isSuperset(of: stringFromTextField as CharacterSet)
return strValid
}
IPhone only solution
In whatever UITextField you're getting these values from, you can specify the kind of keyboard you want to appear when somebody touches inside the text field.
E.G. a numeric-only keyboard.
Like this screenshot:
Ipad
The iPad does not support the numeric keyboard, so your options are to either not support the iPad, validate the field post submit, or follow one of the other suggestions here to create same behaviors while running on an iPad.