Decode nsData to String Array - swift

Question

I want to decode my nsData to a String Array. I have this code right now:
func nsDataToStringArray(data: NSData) -> [String] {
var decodedStrings = [String]()
var stringTerminatorPositions = [Int]()
var currentPosition = 0
data.enumerateBytes() {
buffer, range, stop in
let bytes = UnsafePointer<UInt8>(buffer)
for i in 0 ..< range.length {
if bytes[i] == 0 {
stringTerminatorPositions.append(currentPosition)
}
currentPosition += 1
}
}
var stringStartPosition = 0
for stringTerminatorPosition in stringTerminatorPositions {
let encodedString = data.subdata(with: NSMakeRange(stringStartPosition, stringTerminatorPosition - stringStartPosition))
let decodedString = NSString(data: encodedString, encoding: String.Encoding.utf8.rawValue)! as String
decodedStrings.append(decodedString)
stringStartPosition = stringTerminatorPosition + 1
}
return decodedStrings
}
But I get an error on this line: let bytes = UnsafePointer<UInt8>(buffer)
Cannot invoke initializer for type 'UnsafePointer' with an
argument list of type '(UnsafeRawPointer)'
Do I need to convert the buffer to a UnsafePointer? If so, how can I do that?

Answer 1

buffer in the enumerateBytes() closure is a UnsafeRawPointer
and you have to "rebind" it to an UInt8 pointer in Swift 3:
// let bytes = UnsafePointer<UInt8>(buffer)
let bytes = buffer.assumingMemoryBound(to: UInt8.self)
But why so complicated? You can achieve the same result with
func nsDataToStringArray(nsData: NSData) -> [String] {
let data = nsData as Data
return data.split(separator: 0).flatMap { String(bytes: $0, encoding: .utf8) }
}
How does this work?
Data is a Sequence of UInt8, therefore
split(separator: 0) can be called on it, returning an array of
"data slices" (which are views into the source data, not copies).
Each "data slice" is again a Sequence of UInt8, from which a
String can be created with String(bytes: $0, encoding: .utf8).
This is a failable initializer (because the data may be invalid UTF-8).
flatMap { ... } returns an array with all non-nil results,
i.e. an array with all strings which could be created from
valid UTF-8 code sequences between zero bytes.