UITextField : restrict the maximum allowed value (number) during inputting

Question

I have a UITextField, I\'d like to restrict the maximum allowed input value in the field to be 1000. That\'s when user is inputting number inside, once the inpu

Answer 1

You should do the following inside the above method:

NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];

//first, check if the new string is numeric only. If not, return NO;
NSCharacterSet *characterSet = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789,."] invertedSet];
if ([newString rangeOfCharacterFromSet:characterSet].location != NSNotFound)
{
    return NO;
}

return [newString doubleValue] < 1000;

Answer 2

I created a class with the help method that can be call from any place in your project.

Swift code:

class TextFieldUtil: NSObject {

    //Here I am using integer as max value, but can change as you need
    class func validateMaxValue(textField: UITextField, maxValue: Int, range: NSRange, replacementString string: String) -> Bool {

        let newString = (textField.text! as NSString).stringByReplacingCharactersInRange(range, withString: string)

        //if delete all characteres from textfield
        if(newString.isEmpty) {
            return true
        }

        //check if the string is a valid number
        let numberValue = Int(newString)

        if(numberValue == nil) {
            return false
        }

        return numberValue <= maxValue
    }
}

Then you can use in your uiviewcontroller, in textfield delegate method with any textfield validations

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    if(textField == self.ageTextField) {
        return TextFieldUtil.validateMaxValue(textField, maxValue: 100, range: range, replacementString: string)
    }
    else if(textField == self.anyOtherTextField) {
        return TextFieldUtils.validateMaxValue(textField, maxValue: 1200, range: range, replacementString: string)
    }
    return true
}

Answer 3

In its most basic form you can do this:

- (BOOL)textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range
replacementString:(NSString*)string
{
    NSString* newText;

    newText = [textField.text stringByReplacingCharactersInRange:range withString:string];

    return [newText intValue] < 1000;
}

However, you also need to check if newText is an integer, because intValue returns 0 when the text starts with other characters.

Answer 4

if([string length])
{
  if (textField == txt)
  {
      NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];
      return !([newString length] > 1000);
  }                     
}

Answer 5

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    if(textField.tag == 3)
    {
        if(textField.text.length >3 && range.length == 0)
        {
            return NO;
        }
        else
        {
            return YES;
        }
    }
}