Enums and Pattern Matching

Associated Values

Enum cases can carry data that belongs to that case.

Store data with a case

associated_values.swift 
enum Measurement {
    case centimeters(Int)
    case inches(Int)
}

let useMetric = 
let measurement: Measurement

if useMetric {
    measurement = Measurement.centimeters(30)
} else {
    measurement = Measurement.inches(12)
}

var label = ""
switch measurement {
case Measurement.centimeters(let value):
    label = "cm=\(value)"
case Measurement.inches(let value):
    label = "in=\(value)"
}

print("useMetric=\(useMetric)")
print(label)

enum Measurement {
    case centimeters(Int)
    case inches(Int)
}

let useMetric = 
let measurement: Measurement

if useMetric {
    measurement = Measurement.centimeters(30)
} else {
    measurement = Measurement.inches(12)
}

var label = ""
switch measurement {
case Measurement.centimeters(let value):
    label = "cm=\(value)"
case Measurement.inches(let value):
    label = "in=\(value)"
}

print("useMetric=\(useMetric)")
print(label)
associated values Associated values keep related data inside the enum value so each case can carry the information it needs.