Swift — Unit Conversions

Objectives

Write functions that solve the problem of converting values between different systems of measure.

Instructions

Open the swift-unit-conversions.xcworkspace file. Navigate to the Sandbox.swift file to write your functions.

You can run the tests using ⌘ U, but you will need to declare all six functions in order to get the build to succeed. If you would like to write your functions one-at-a-time, you may call them with your own test data from the AppDelegate.swift file inside the application:didFinishLaunchingWithOptions: method and running the scheme with ⌘ R. Use the print() function to send your results to the Console Output viewer.

I. Temperature

The United States still widely uses the Fahrenheit system for measuring temperature on a casual basis (weather-related) instead of the more widely-adopted Celsius scale. Both were developed in the 18th Century but calibrate themselves in slightly different ways.

The freezing point of water is:

32 degrees Fahrenheit and
0 degrees Celsius.

The boiling point of water is:

212 degrees Fahrenheit and
100 degrees Celsius.

`fahrenheitFromCelsius(_:)`

Write a function named fahrenheitFromCelsius(_:) which converts a Double argument in degrees Celsius to a Double result in degrees Fahrenheit.

`celsiusFromFahrenheit(_:)`

Write another function named celsiusFromFahrenheit(_:) which converts a Double argument in degrees Fahrenheit to a Double result in degrees Celsius.

Hint: The means that there is a 32 degree (Fahrenheit) offset between the systems, and ratio of 180 degrees Fahrenheit to 100 degrees Celsius—this ratio reduces to the fraction 9/5.

II. Circles

Circular arcs can be measured in either angular degrees or in radians. There are 360 angular degrees in a full circle and 2pi radians in a full circle (which in decimal form is about 6.283~). The Swift Foundation has access to C's math.h library which includes the 48-decimal-point-value of pi accessible as M_PI.

`radiansFromDegrees(_:)`

Write a function named radiansFromDegrees(_:) which converts a Double argument in angular degrees to a Double result in radians.

`degreesFromRadians(_:)`

Write another function named degreesFromRadians(_:) which converts a Double argument in radians to a Double result in angular degrees.

Hint: degrees / 180 * pi = radians

III. Distance

The United States, Liberia, and Burma are the only three countries in the world which still use Imperial Units in favor of the Metric System to measure distance. Miles (mi) and Kilometers (Km) are similarly scaled measures of distance across the two systems.

`milesFromKilometers(_:)`

Write a function named milesFromKilometers(_:) which converts a Double argument in Kilometers (Km) to a Double result in miles (mi).

`kilometersFromMiles(_:)`

Write another function named kilometersFromMiles(_:) which converts a Double argument in miles (mi) to a Double result in kilometers (Km).

Hint: There are approximately 1.60934 Kilometers in one mile. View this lesson on Learn.co

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