Convert a two byte UInt8 array to a UInt16 in Swift

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If you want to go via NSData then it would work like this:

let bytes:[UInt8] = [0x01, 0x02]
println("bytes: \(bytes)") // bytes: [1, 2]
let data = NSData(bytes: bytes, length: 2)
print("data: \(data)") // data: <0102>

var u16 : UInt16 = 0 ; data.getBytes(&u16)
// Or:
let u16 = UnsafePointer<UInt16>(data.bytes).memory

println("u16: \(u16)") // u16: 513

Alternatively:

let bytes:[UInt8] = [0x01, 0x02]
let u16 = UnsafePointer<UInt16>(bytes).memory
print("u16: \(u16)") // u16: 513

Both variants assume that the bytes are in the host byte order.

Update for Swift 3 (Xcode 8):

let bytes: [UInt8] = [0x01, 0x02]
let u16 = UnsafePointer(bytes).withMemoryRebound(to: UInt16.self, capacity: 1) {
    $0.pointee
}
print("u16: \(u16)") // u16: 513

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