How to convert a float value to byte array in swift?

Question

The code which I am using for getting data in bytes, but I am not getting correct byte data for float value

let count = data.length / sizeof(UInt32)

// create array of appropriate length:
var array = [UInt32](count: count, repeatedValue: 0)

// copy bytes into array
data.getBytes(&array, length:count * sizeof(UInt32))

print(array)

Answer 1

Float to NSData:

var float1 : Float = 40.0
let data = NSData(bytes: &float1, length: sizeofValue(float1))
print(data) // <00002042>

... and back to Float:

var float2 : Float = 0
data.getBytes(&float2, length: sizeofValue(float2))
print(float2) // 40.0

(The same would work for other "simple" types like Double, Int, ...)

Update for Swift 3, using the new Data type:

var float1 : Float = 40.0
let data = Data(buffer: UnsafeBufferPointer(start: &float1, count: 1))
print(data as NSData) // <00002042>

let float2 = data.withUnsafeBytes { $0.pointee } as Float
print(float2) // 40.0

(See also round trip Swift number types to/from Data)

Update for Swift 4 and later:

var float1 : Float = 40.0
let data = Data(buffer: UnsafeBufferPointer(start: &float1, count: 1))

let float2 = data.withUnsafeBytes { $0.load(as: Float.self) } 
print(float2) // 40.0

Remark: load(as:) requires the data to be properly aligned, for Float that would be on a 4 byte boundary. See e.g. round trip Swift number types to/from Data for other solutions which work for arbitrarily aligned data.