NSMutableString *filteredPhoneStringFromStringWithFilter(NSString *string, NSString *filter)
{
NSUInteger onOriginal = 0, onFilter = 0, onOutput = 0;
char outputString[([filter length])];
BOOL done = NO;
while(onFilter < [filter length] && !done)
{
char filterChar = [filter characterAtIndex:onFilter];
char originalChar = onOriginal >= string.length ? '\0' : [string characterAtIndex:onOriginal];
switch (filterChar) {
case '#':
if(originalChar=='\0')
{
// We have no more input numbers for the filter. We're done.
done = YES;
break;
}
if(isdigit(originalChar))
{
outputString[onOutput] = originalChar;
onOriginal++;
onFilter++;
onOutput++;
}
else
{
onOriginal++;
}
break;
default:
// Any other character will automatically be inserted for the user as they type (spaces, - etc..) or deleted as they delete if there are more numbers to come.
outputString[onOutput] = filterChar;
onOutput++;
onFilter++;
if(originalChar == filterChar)
onOriginal++;
break;
}
}
outputString[onOutput] = '\0'; // Cap the output string
return [NSMutableString stringWithUTF8String:outputString];
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSString *filter = @"##/##/####";
if(!filter) return YES; // No filter provided, allow anything
NSString *changedString = [textField.text stringByReplacingCharactersInRange:range withString:string];
if(range.length == 1 && // Only do for single deletes
string.length < range.length &&
[[textField.text substringWithRange:range] rangeOfCharacterFromSet:[NSCharacterSet characterSetWithCharactersInString:@"0123456789"]].location == NSNotFound)
{
// Something was deleted. Delete past the previous number
NSInteger location = changedString.length-1;
if(location > 0)
{
for(; location > 0; location--)
{
if(isdigit([changedString characterAtIndex:location]))
{
break;
}
}
changedString = [changedString substringToIndex:location];
}
}
textField.text = filteredPhoneStringFromStringWithFilter(changedString, filter);
return NO;
}
