Swift double to string

Question

Before I updated xCode 6  I had no problems casting a double to a string but now it gives me an error  var a  Double   1 5 var b  String   String a    It gives me the error message  double is not convertible to string   Is there any other way to do it

User · Answer

This function will let you specify the number of decimal places to show:

func doubleToString(number:Double, numberOfDecimalPlaces:Int) -> String {
    return String(format:"%."+numberOfDecimalPlaces.description+"f", number)
}

Usage:

let numberString = doubleToStringDecimalPlacesWithDouble(number: x, numberOfDecimalPlaces: 2)

User · Answer

There are many answers here that suggest a variety of techniques  But when presenting numbers in the UI  you invariably want to use a NumberFormatter so that the results are properly formatted  rounded  and localized   let value   10000 5  let formatter   NumberFormatter   formatter numberStyle    decimal  guard let string   formatter string for  value  else   return   print string     10 000 5   If you want fixed number of decimal places  e g  for currency values  let value   10000 5  let formatter   NumberFormatter   formatter numberStyle    decimal formatter maximumFractionDigits   2 formatter minimumFractionDigits   2  guard let string   formatter string for  value  else   return   print string     10 000 50   But the beauty of this approach  is that it will be properly localized  resulting in 10 000 50 in the US but 10 000 50 in Germany  Different locales have different preferred formats for numbers  and we should let NumberFormatter use the format preferred by the end user when presenting numeric values within the UI   Needless to say  while NumberFormatter is essential when preparing string representations within the UI  it should not be used if writing numeric values as strings for persistent storage  interface with web services  etc

User · Answer

Swift 3   Try these line of code  let num  Double   1 5  let str   String format     2f   num

User · Answer

In Swift 4 if you like to modify and use a Double in the UI as a textLabel  String  you can add this in the end of your file       extension Double   func roundToInt   - gt  Int      return Int Darwin round self          And use it like this if you like to have it in a textlabel   currentTemp text      weatherData tempCelsius roundToInt       Or print it as an Int   print weatherData tempCelsius roundToInt

User · Answer

In swift 3 it is simple as given below  let stringDouble    String describing  double

User · Answer

to make anything a string in swift except maybe enum values simply do what you do in the println   method   for example    var stringOfDBL      myDouble

User · Answer

In swift 3   var a  Double   1 5 var b  String   String a

User · Answer

let double   1 5  let string   double description  update Xcode 7 1     Swift 2 1  Now Double is also convertible to String so you can simply use it as you wish  let double   1 5 let doubleString   String double        quot 1 5 quot   Swift 3 or later we can extend LosslessStringConvertible and make it generic Xcode 11 3     Swift 5 1 or later extension LosslessStringConvertible        var string  String    init self         let double   1 5  let string   double string       quot 1 5 quot    For a fixed number of fraction digits we can extend FloatingPoint protocol  extension FloatingPoint where Self  CVarArg       func fixedFraction digits  Int  - gt  String            init format   quot    f quot   digits  self            If you need more control over your number format  minimum and maximum fraction digits and rounding mode  you can use NumberFormatter  extension Formatter       static let number   NumberFormatter       extension FloatingPoint       func fractionDigits min  Int   2  max  Int   2  roundingMode  NumberFormatter RoundingMode    halfEven  - gt  String           Formatter number minimumFractionDigits   min         Formatter number maximumFractionDigits   max         Formatter number roundingMode   roundingMode         Formatter number numberStyle    decimal         return Formatter number string for  self      quot  quot            2 12345 fractionDigits                                          quot 2 12 quot  2 12345 fractionDigits min  3  max  3  roundingMode   up        quot 2 124 quot

User · Answer

var b   String stringInterpolationSegment  a    This works for me  You may have a try

User · Answer

I would prefer NSNumber and NumberFormatter approach  where need   also u can use extension to avoid bloating code  extension Double       var toString  String         return NSNumber value  self  stringValue           U can also need reverse approach  extension String        var toDouble  Double           return Double self      nan

User · Answer

Swift 5   Use following code  extension Double        func getStringValue withFloatingPoints points  Int   0  - gt  String           let valDouble   modf self          let fractionalVal    valDouble 1          if fractionalVal  gt  0               return String format      f   points  self                    return String format     0f   self

User · Answer

In addition to  Zaph answer  you can create extension   extension Double       func toString   - gt  String           return String format     1f  self              Usage   var a Double   1 5 println  output    a toString          output  1 5

User · Answer

It is not casting  it is creating a string from a value with a format  let a  Double   1 5 let b  String   String format   quot  f quot   a   print  quot b    b  quot      b  1 500000  With a different format  let c  String   String format   quot   1f quot   a   print  quot c    c  quot      c  1 5  You can also omit the format property if no formatting is needed

User · Answer

Swift 4   Use following code  let number   2 4 let string   String format     2f   number

[swift] Swift double to string

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