Swift 型変換まとめ

Swiftに限らずだけど型変換はよく忘れるので備忘録

Int

Int -> String

let intNum : Int = 17
let stringNum : String = String(intNum)
print(stringNum) // 17

Int -> Double

let intNum : Int = 17
let doubleNum: Double = Double(intNum)
print(doubleNum) // 17.0

Int -> Float

let intNum : Int = 17
let floatNum: Float = Float(intNum)
print(floatNum) // 17.0

Float

Float -> String

let floatNum : Float = 17.5
let stringNum : String = String(floatNum)
print(stringNum) // 17.5

Float -> Int (小数点切り捨て)

let floatNum : Float = 17.5
let intNum : Int = Int(floatNum)
print(intNum) // 17

Float -> Double

let floatNum : Float = 17.5
let doubleNum : Double = Double(floatNum)
print(doubleNum) // 17.5

Double

Double -> String

let doubleNum: Double = 17.5
let stringNum : String = String(doubleNum)
print(stringNum) // 17.5

Double -> Int (小数点切り捨て)

let doubleNum : Double = 17.5
let intNum : Int = Int(doubleNum)
print(intNum) // 17

Double -> Float

let doubleNum : Double = 17.5
let floatNum : Float = Float(doubleNum)
print(floatNum) // 17.5

String

String -> Int(整数以外を指定した場合はnil)

let stringNum : String = "17"
let intNum : Int = Int(stringNum)
print(intNum) // 17

let stringNum : String = "17.5"
let intNum : Int? = Int(stringNum)
print(intNum) // nil

String -> Double(String -> Double変換はatof使う方法も)

let stringNum : String = "10.59"
let doubleNum : Double = Double(stringNum)!
print(doubleNum) // 10.59

import Darwin

let stringNum : String = "10.59"
let doubleNum : Double = atof(stringNum)
print(doubleNum) // 10.59

String -> Float

let stringNum : String = "17.5"
let floatNum : Float = Float(stringNum)
print(floatNum) // 17.5

Bool

Bool -> String

let bool : Bool = true
let stringBool : String = String(bool)
print(stringBool) // true

Bool -> Int

let bool : Bool = true
let intBool : Int = Int(bool)
print(intBool) // 1

Bool -> Float

let bool : Bool = true
let floatBool : Float = Float(bool)
print(floatBool) // 1.0

Bool -> Double

let bool : Bool = true
let doubleBool : Double = Double(bool)
print(doubleBool) // 1.0
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