How to convert bytes to a float value in swift?

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<44fa0000> is the big-endian memory representation of the
binary floating point number 2000.0. To get the number back from
the data, you have to read it into an UInt32 first, convert from
big-endian to host byteorder, and then cast the result to
a Float.

In Swift 2 that would be

func floatValueFromData(data: NSData) -> Float {
    return unsafeBitCast(UInt32(bigEndian: UnsafePointer(data.bytes).memory), Float.self)
}

Example:

let bytes: [UInt8] =  [0x44, 0xFA, 0x00, 0x00]
let data = NSData(bytes: bytes, length: 4)

print(data) // <44fa0000>
let f = floatValueFromData(data)
print(f) // 2000.0

In Swift 3 you would use Data instead of NSData, and the
unsafeBitCast can be replaced by the Float(bitPattern:)
initializer:

func floatValue(data: Data) -> Float {
    return Float(bitPattern: UInt32(bigEndian: data.withUnsafeBytes { $0.pointee } ))
}

In Swift 5 the withUnsafeBytes() method of Data calls the closure with an (untyped) UnsafeRawBufferPointer, and you can load() the value from the raw memory:

func floatValue(data: Data) -> Float {
    return Float(bitPattern: UInt32(bigEndian: data.withUnsafeBytes { $0.load(as: UInt32.self) }))
}

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