Xcode 11 • Swift 5.1 or later
To convert from String
or any Numeric
type to Data
:
extension StringProtocol {
var data: Data { .init(utf8) }
}
extension Numeric {
var data: Data {
var source = self
// This will return 1 byte for 8-bit, 2 bytes for 16-bit, 4 bytes for 32-bit and 8 bytes for 64-bit binary integers. For floating point types it will return 4 bytes for single-precision, 8 bytes for double-precision and 16 bytes for extended precision.
return .init(bytes: &source, count: MemoryLayout<Self>.size)
}
}
To convert from Data
(bytes) back to String
extension DataProtocol {
var string: String? { String(bytes: self, encoding: .utf8) }
}
To convert from Data
back to generic Numeric
value
extension Numeric {
init<D: DataProtocol>(_ data: D) {
var value: Self = .zero
let size = withUnsafeMutableBytes(of: &value, { data.copyBytes(to: $0)} )
assert(size == MemoryLayout.size(ofValue: value))
self = value
}
}
extension DataProtocol {
func value<N: Numeric>() -> N { .init(self) }
}
let value = 12.34 // implicit Double 12.34
let data = value.data // double data - 8 bytes
let double = Double(data) // implicit Double 12.34
let double1: Double = .init(data) // explicit Double 12.34
let double2: Double = data.value() // explicit Double 12.34
let double3 = data.value() as Double // casting to Double 12.34
Now we can easily add a property for each Numeric
type:
extension DataProtocol {
var integer: Int { value() }
var int32: Int32 { value() }
var float: Float { value() }
var cgFloat: CGFloat { value() }
var float80: Float80 { value() }
var double: Double { value() }
var decimal: Decimal { value() }
}
Playground testing
let intData = 1_234_567_890_123_456_789.data // 8 bytes (64 bit Integer)
let dataToInt: Int = intData.integer // 1234567890123456789
let intMinData = Int.min.data // 8 bytes (64 bit Integer)
let backToIntMin = intMinData.integer // -9223372036854775808
let intMaxData = Int.max.data // 8 bytes (64 bit Integer)
let backToIntMax = intMaxData.integer // 9223372036854775807
let myInt32Data = Int32(1_234_567_890).data // 4 bytes (32 bit Integer)
let backToInt32 = myInt32Data.int32 // 1234567890
let int32MinData = Int32.min.data // 4 bytes (32 bit Integer)
let backToInt32Min = int32MinData.int32 // -2147483648
let int32MaxData = Int32.max.data // 4 bytes (32 bit Integer)
let backToInt32Max = int32MaxData.int32 // 2147483647
let myFloatData = Float.pi.data // 4 bytes (32 bit single=precison FloatingPoint)
let backToFloat = myFloatData.float // 3.141593
backToFloat == .pi // true
let myCGFloatData = CGFloat.pi.data // 4 bytes (32 bit single=precison FloatingPoint)
let backToCGFloat = myCGFloatData.cgFloat // 3.141593
backToCGFloat == .pi // true
let myDoubleData = Double.pi.data // 8 bytes (64 bit double-precision FloatingPoint)
let backToDouble = myDoubleData.double // 3.141592653589793
backToDouble == .pi // true
let myFloat80Data = Float80.pi.data // 16 bytes (128 bit extended-precision FloatingPoint)
let backToFloat80 = myFloat80Data.float80 // 3.141592653589793116
backToFloat80 == .pi // true
let decimalData = Decimal.pi.data // 20 bytes Decimal type
let backToDecimal = decimalData.decimal // 3.14159265358979323846264338327950288419
backToDecimal == .pi // true
let stringBytes = "Hello World !!!".data.prefix(4) // 4 bytes
let backToString = stringBytes.string // "Hell"