Swift: extract float from byte data

Question

I\'m looking for a robust and elegant way to extract four big-endian bytes from an array as a Float.

I can get a UInt32 with the bits via something like this:

<

Answer 1

The floating point types have a static _fromBitPattern that will return a value. <Type>._BitsType is a type alias to the correctly sized unsigned integer:

let data: [Byte] = [0x00, 0x00, 0x00, 0x40, 0x86, 0x66, 0x66, 0x00]
let dataPtr = UnsafePointer<Byte>(data)
let byteOffset = 3
let bits = UnsafePointer<Float._BitsType>(dataPtr + byteOffset)[0].bigEndian
let f = Float._fromBitPattern(bits)

You don't see that method in auto-completion, but it's a part of the FloatingPointType protocol. There's an instance method that will give you back the bits, called ._toBitPattern().

Answer 2

Here's the solution for Swift 3:

Float(bitPattern: bits)

Answer 3

The equivalent Swift code is

let flt = unsafeBitCast(bits, Float.self)

which gives 4.2 with your data.