Guide to Swift Numbers Sample Code

Chapter 1

Floating Point Approximates

0.1+0.2==0.3 // false0.1+0.2==~0.3 // true(0.1+0.2).isApproximatelyEqual(to:0.3, within:.ulpOfOne) // true

Floating Point Environment

do{trydetectingFloatingPointErrors(flags:.invalid){Double.signalingNaN+1}}catch{print("Error:\(error)")}

Chapter 2

Cardinal Numbers

letformatter=NumberFormatter()formatter.string(for:4) // 4formatter.numberStyle=.spellOutformatter.string(for:4) // four

Ordinal Numbers

letformatter=NumberFormatter()formatter.numberStyle=.ordinalformatter.string(for:1) // 1st

Decimal Numbers

letformatter=NumberFormatter()formatter.numberStyle=.decimalformatter.string(for:1234567.89)1,234,567.89

Significant Digits

letformatter=NumberFormatter()formatter.usesSignificantDigits=trueformatter.maximumSignificantDigits=2formatter.string(from:123) // 120formatter.string(from:123456) // 120000formatter.string(from:123.456) // 120formatter.string(from:1.230000) // 1.2formatter.string(from:0.00123) // 0.0012

Integer and Fraction Digits

letformatter=NumberFormatter()formatter.usesSignificantDigits=false // defaultformatter.minimumIntegerDigits=4formatter.minimumFractionDigits=2formatter.string(from:123) // 0123.00formatter.string(from:123456) // 123456.00formatter.string(from:123.456) // 0123.46formatter.string(from:1.230000) // 0001.23formatter.string(from:0.00123) // 0000.00

Rounding Modes

letformatter=NumberFormatter()formatter.numberStyle=.decimalformatter.maximumFractionDigits=1letnumbers=[1.2,1.22,1.25,1.27,-1.25]letmodes:[NumberFormatter.RoundingMode]=[.ceiling,.floor,.up,.down,.halfUp,.halfDown,.halfEven]formodein modes{    formatter.roundingMode= modefornumberin numbers{        formatter.string(for: number)}}

Scientific Notation

letformatter=NumberFormatter()formatter.numberStyle=.scientificformatter.string(for:12345.6789) // 1.23456789E4

Percentages

letformatter=NumberFormatter()formatter.numberStyle=.percentformatter.string(for:0.12) // 12%

Currencies

letformatter=NumberFormatter()letidentifiers=["en-US","en-GB","de-DE","ja-JP"]letstyles:[NumberFormatter.Style]=[.currency,.currencyAccounting,.currencyISOCode,.currencyPlural]forstylein styles{    formatter.numberStyle= styleforidentifierin identifiers{        formatter.locale=Locale(identifier: identifier)        formatter.string(for:1234.567)}}

Custom Formats

letformatter=NumberFormatter()formatter.numberStyle=.decimal// Format with thousands and decimal separator// that rounds to the nearest five tenthsformatter.format="#,##0.5"formatter.locale=Locale(identifier:"en-US")formatter.string(for:1234.567) // 1,234.5formatter.locale=Locale(identifier:"fr-FR")formatter.string(for:1234.567) // 1 234,5

Chapter 3

Money

letprices:[Money<USD>]=[2.19,5.39,20.99,2.99,1.99,1.99,0.99]letsubtotal= prices.reduce(0.00,+)lettax=0.08* subtotallettotal= subtotal+ tax // $39.45

Currency Converter

letEURtoUSD=CurrencyPair<EUR,USD>(rate:1.17) // as of June 1st, 2018leteuroAmount:Money<EUR>=123.45letdollarAmount=EURtoUSD.convert(euroAmount) // $144.44

Chapter 4

Natural Scale

letlengthOfRoom=Measurement<UnitLength>(value:8, unit:.meters)letdistanceToAirport=Measurement<UnitLength>(value:16, unit:.kilometers)letformatter=MeasurementFormatter()formatter.unitOptions=.naturalScaleformatter.string(from: lengthOfRoom) // 26.247 ftformatter.string(from: distanceToAirport) // 9.942 mi

Provided Units

letingotMass=Measurement<UnitMass>(value:400, unit:.ouncesTroy)letformatter=MeasurementFormatter()formatter.unitOptions=.providedUnitformatter.string(from: ingotMass) // 400 oz t

Configuring Precision

letbarometerReading=Measurement<UnitPressure>(value:29.9, unit:.inchesOfMercury)letpressureInMillibars= barometerReading.converted(to:.millibars)letformatter=MeasurementFormatter()formatter.unitOptions=.providedUnitformatter.numberFormatter.usesSignificantDigits=trueformatter.numberFormatter.maximumSignificantDigits=3formatter.string(from: pressureInMillibars) // 1,010 mbar

Temperature Formatting

lettemperatureInF=Measurement<UnitTemperature>(value:72, unit:.fahrenheit)lettemperatureInC=Measurement<UnitTemperature>(value:20.5, unit:.celsius)letformatter=MeasurementFormatter()formatter.locale=Locale(identifier:"en-US")formatter.string(from: temperatureInF) // 72°Fformatter.string(from: temperatureInC) // 68.9°Fformatter.locale=Locale(identifier:"fr-FR")formatter.string(from: temperatureInF) // 22,222 °Cformatter.string(from: temperatureInC) // 20,5 °Cformatter.unitOptions=.temperatureWithoutUnitformatter.locale=Locale(identifier:"en-US")formatter.string(from: temperatureInF) // 72°formatter.string(from: temperatureInC) // 20.5° (!)formatter.locale=Locale(identifier:"fr-FR")formatter.string(from: temperatureInF) // 72° (!)formatter.string(from: temperatureInC) // 20,5°

Units Interoperability

letloggedFlyingTime=Measurement<UnitDuration>(value:220, unit:.hours)letformatter=DateComponentsFormatter()formatter.allowedUnits=[.day]formatter.unitsStyle=.fullformatter.includesApproximationPhrase=trueformatter.string(from: loggedFlyingTime) // About 9 days

Chapter 5

Agricultural Flight Planner

lettakeoffWeight=(    emptyPlaneWeight+    payloadWeight+    fuelWeight+    pilotWeight).converted(to:.pounds)letcanTakeOff= takeoffWeight< maximumTakeoffWeight // ???

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