How can I limit the number of decimal points in a UITextField?

Question

I have a UITextField that when clicked brings up a number pad with a decimal point in the bottom left. I am trying to limit the field so that a user can only place 1 decimal mark

e.g.
2.5 OK
2..5 NOT OK

Answer 1

Implement the shouldChangeCharactersInRange method like this:

// Only allow one decimal point // Example assumes ARC - Implement proper memory management if not using. - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string  {     NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];     NSArray  *arrayOfString = [newString componentsSeparatedByString:@"."];      if ([arrayOfString count] > 2 )          return NO;      return YES; } 

This creates an array of strings split by the decimal point, so if there is more than one decimal point we will have at least 3 elements in the array.

Answer 2

Here is an example with a regular expression, the example limits to only one decimal point and 2 decimals. You can tweak it to fit your needs.

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {     NSString *newString = [textField.text stringByReplacingCharactersInRange:range withString:string];     NSString *expression = @"^[0-9]*((\\.|,)[0-9]{0,2})?$";     NSError *error = nil;     NSRegularExpression *regex = [NSRegularExpression regularExpressionWithPattern:expression options:NSRegularExpressionCaseInsensitive error:&error];     NSUInteger numberOfMatches = [regex numberOfMatchesInString:newString options:0 range:NSMakeRange(0, [newString length])];     return numberOfMatches != 0; }