precision(_:)
Modifies the format style to use the specified precision.
Declaration
func precision(_ p: FloatingPointFormatStyle<Value>.Configuration.Precision) -> FloatingPointFormatStyle<Value>Parameters
- p:
The precision to apply to the format style.
Return Value
A floating-point format style modified to use the specified precision.
Discussion
The NumberFormatStyleConfiguration.Precision type lets you specify a fixed number of digits to show for a number’s integer and fractional parts. You can also set a fixed number of significant digits.
The following example creates a default FloatingPointFormatStyle for the en_US locale, and a second style that uses a maximum of four significant digits. It then applies each style to an array of floating-point values. The formatting that the modified style applies truncates precision to 0 after the fourth most-significant digit.
let defaultStyle = FloatingPointFormatStyle<Double>(locale: Locale(identifier: "en_US"))
let precisionStyle = defaultStyle.precision(.significantDigits(1...4))
let nums = [123.1, 1234.1, 12345.1, 123456.1, 1234567.1]
let defaultNums = nums.map { defaultStyle.format($0) } // ["123.1", "1,234.1", "12,345.1", "123,456.1", "1,234,567.1"]
let precisionNums = nums.map { precisionStyle.format($0) } // ["123.1", "1,234", "12,350", "123,500", "1,235,000"]