How to show 2 decimal places regardless of the number of digits after the decimal fraction?

Question

I am writing an application in swift and used the code below. Thus, my result is rounded to two decimal places, as expected.

It works well. However, if the result is less than 2 decimal places, it only shows 1 digit. This is the most basic example, but I have results that can be an integer or 10 decimal places. I want them all to display as .xx

 1.2345 => 1.23 1.1 => 1.1 

How do I get results to always show 2 decimal places regardless of the number of digits after the decimal point?

For example: 1.1 => 1.10

I searched many times, but the answer eluded me. This is the code I've tried so far:

 @IBOutlet var odds: UITextField! @IBOutlet var oddsLabel: UILabel! var enteredOdds = NSString(string: odds.text).doubleValue var numberOfPlaces = 2.0 var multiplier = pow(10.0, numberOfPlaces) var enteredOddsRounded = round(enteredOdds * multiplier) / multiplier oddsLabel.text = "\(enteredOddsRounded)" println("\(enteredOddsRounded)") 

Thanks for the comments. I made the changes as follows:

 @IBOutlet var odds: UITextField! @IBOutlet var oddsLabel: UILabel! var enteredOdds = NSString(string: odds.text).doubleValue let formatter = NSNumberFormatter() formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle for identifier in ["en_UK", "eu_US"] { formatter.locale = NSLocale(localeIdentifier: identifier) formatter.minimumFractionDigits = 2 formatter.maximumFractionDigits = 2 } oddsLabel.text = formatter.stringFromNumber(enteredOdds) 

This allowed me to lose a lot of code, since it rounds off and decimal numbers for me, and also includes currency as a bonus.

Thile, this worked for all fields where I really needed a currency to display. The above value of "oddsLabel.text" is not really a currency and therefore allows rounding and decimal places.

How to change the above so that it can take into account fields with and / or without currency. Hopefully not repeating the code again?

Thanks again for all the quick answers.

Franc

Answer 1

 let b = 2.1 println(String(format:"%.02f", b)) 

gives the string "2.10" on my playground.

Answer 2

What you used is called a "naive" implementation. It works mostly, but it has some minor problems and some hidden problems. One of the hidden problems is that you completely ignore the user language - most European languages ​​use a comma as a decimal separator, not a period.

To deal with the decimal problem with string conversion (and vice versa), most programming languages ​​provide a dedicated API. Cocoa / CocoaTouch has an NSNumberFormatter .

Example:

 let formatter = NumberFormatter() formatter.numberStyle = .decimal formatter.minimumFractionDigits = 2 formatter.maximumFractionDigits = 2 oddsLabel.text = formatter.stringFromNumber(enteredOdds) 

Please note that rounding is done for you.

Answer 3

You may be looking for NSNumberFormatter :

 let nf = NSNumberFormatter() nf.minimumFractionDigits = 2 nf.stringFromNumber(enteredOddsRounded) 

Answer 4

Extension for setting the minimum digits of digits:

  extension String { func setMinTailingDigits() -> String { let formatter = NumberFormatter() formatter.minimumFractionDigits = 2 return formatter.string(from: Double(self)! as NSNumber)! } } 

Answer 5

 oddsLabel.text = (NSString(format:"%.2f", enteredOddsRounded)) 

This is what I use in some cases.

there is also an option to use NSNumberFormatter, where you can also add commas

here is the tutorial http://nshipster.com/nsformatter/