I’m fairly new to -c and not sure how to fix this error.

@property (nonatomic, retain) NSString *tempStore;

———

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if ([string length] > 0) { //NOT A BACK SPACE Add it

self.tempStore = [NSString stringWithFormat:@"%@%@", self.tempStore, string];
} else {
//Back Space do manual backspace
if ([self.tempStore length] > 1) {
self.tempStore = [self.tempStore substringWithRange:NSMakeRange(0, [self.tempStore length]-1)];
} else {self.tempStore = @”0″;}

}
// Convert to decimal place
float tempDouble = [self.tempStore floatValue];
tempDouble = tempDouble / 100;
textField.text = [NSString stringWithFormat:@"$%.2f", tempDouble];
return NO;
}

Yep, this is only viable for currency and other values where the decimal can be inferred. For instance, this would also work for measurements with fixed precisions like medical dosages (never more than 2 or 4 decimal places).

And yes, you are right in that it does require 2 extra taps for currency values ending in .00. However, this only occurs 1% of the time.

So, as compared to a decimal button design, this design…

1% of the time requires 2 extra taps (whole amounts; eg $123.00)

9% of the time requires the same number of taps (amounts ending in multiples of 10 cents; eg, $123.10)

90% of the time saves 1 tap (all other amounts; eg $123.45)

My guess as to why Apple doesn’t provide a stock keypad with a decimal point is that it is not that common of a use-case. If you use the design outlined in this post you will hit most of the use cases where people are asking for a decimal button today. In other words, the number of apps today that legitimately require just 0-9, decimal, and backspace buttons are very few and not worth introducing another NumericKeypad option to include the decimal button.

As for Apple offering a custom keypad API, I don’t see the need. Additionally, I think creating a first-class, generic UI API to construct a keypad would be difficult. With the 1.2 update to Gratuitous, I rolled my own keypad (details in a future blog post) and it was surprisingly simple.

Thanks for the feedback and your thoughts on this post, I really appreciate it!

Of course, to enter $123.00, it requires two extra taps, like an ATM machine. And as John Smith noted, this only works for the familiar currency situation.

There’s no excuse for Apple not to have a decimal point option on a numeric keypad! Or a public API facility for building custom keypads.

I saw you comment on my question about the keyboard on stackoverflow. Unfortunately in my case I am not dealing with fixed decimal points so I really do need a decimal point.

Your solution here would only work in certain situations.

Still be interested in seeing how you handled it as I’m doing conversions from NSString to NSDecimalNumber with and back NSNumberFormatters involved upon ever single “key” press from the user. but, it’s working!