UITextField: backspace not working - iphone

Question

I have an issue with UITextField's validation. I want to validate the UITextField's text-length to be 5(fixed).
my code :
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if(textField==codeTxt)
{
NSCharacterSet *unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:NUMBERS]invertedSet] ;
if ([[string componentsSeparatedByCharactersInSet:unacceptedInput] count] > 1)
return NO;
else if ([codeTxt.text length] >= 5])
return NO;
else
return YES;
}
}
this code works fine. It validates and ignores rest of the text(more thn 5).
my problem :
When I press Delete(Backspace), nothing happens !!! the text remains the same. delete(Backspace) does not work.
what could be the problem ?
Thanks...

Answer 1

put this condition at first statement in shouldChangeCharactersInRange method
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if([string length]==0)
{
return YES;
}
if(textField==codeTxt)
{
NSCharacterSet *unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:NUMBERS]invertedSet] ;
if ([[string componentsSeparatedByCharactersInSet:unacceptedInput] count] > 1)
return NO;
else if ([codeTxt.text length] >= 5])
return NO;
else
return YES;
}
}

Answer 2

Your only checking the length of the current text in the field. This method gets called before the text changes, so you need to check the replacementString's length first, then check the textField's text length.
Try this:
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
if (textField == codeTxt) {
// NSCharacterSet *unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:NUMBERS] invertedSet];
// if ([[string componentsSeparatedByCharactersInSet:[unacceptedInput count]] > 1) {
if ([[string componentsSeparatedByCharactersInSet:[[[NSCharacterSet characterSetWithCharactersInString:NUMBERS] invertedSet] autorelease]] count] > 1) {
return NO;
} else if ([string length] < 5) {
return YES;
} else if ([codeTxt.text length] >= 5]) {
return NO;
} else {
return YES;
}
}
}
Edit:
Checking the textField's length probably isn't even necessary after doing [codeTxt.text length] >= 5] since this will prevent the textField's length from ever going above 4 anyway.
Actually, you would need to check it since the default is to return YES;.
Probably needs to be <= 5
} else if ([string length] <= 5) {
return YES;
}
Instead of < 5 too
} else if ([string length] < 5) {
return YES;
}

Answer 3

I got the solution
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if(textField==codeTxt)
{
NSCharacterSet *unacceptedInput = [[NSCharacterSet characterSetWithCharactersInString:NUMBERS]invertedSet] ;
NSLog(#"textfield character validation method called");
NSLog(#"%d",[codeTxt.text length]);
if ([[string componentsSeparatedByCharactersInSet:unacceptedInput] count] > 1)
return NO;
else if ([codeTxt.text length] >= 5 && ![string isEqual:#""])
return NO;
else
return YES;
}
}