SHA256 in swift

Question

I want to use sha256 in my project, but I had some troubles rewriting objC code to swift code. Help me please. I used this answer: How can I compute a SHA-2 (ideally SHA 256 or SHA 512) hash in iOS?

Here's my code

var hash : [CUnsignedChar]
CC_SHA256(data.bytes, data.length, hash)
var res : NSData = NSData.dataWithBytes(hash, length: CC_SHA256_DIGEST_LENGTH)

it gives me error everything because swift cannot convert Int to CC_LONG, for example.

Answer 1

You have to convert explicitly between Int and CC_LONG, because Swift does not do implicit conversions, as in (Objective-)C.

You also have to define hash as an array of the required size.

func sha256(data : NSData) -> NSData {
    var hash = [UInt8](count: Int(CC_SHA256_DIGEST_LENGTH), repeatedValue: 0)
    CC_SHA256(data.bytes, CC_LONG(data.length), &hash)
    let res = NSData(bytes: hash, length: Int(CC_SHA256_DIGEST_LENGTH))
    return res
}

Alternatively, you can use NSMutableData to allocate the needed buffer:

func sha256(data : NSData) -> NSData {
    let res = NSMutableData(length: Int(CC_SHA256_DIGEST_LENGTH))
    CC_SHA256(data.bytes, CC_LONG(data.length), UnsafeMutablePointer(res.mutableBytes))
    return res
}

Update for Swift 3 and 4:

func sha256(data : Data) -> Data {
    var hash = [UInt8](repeating: 0,  count: Int(CC_SHA256_DIGEST_LENGTH))
    data.withUnsafeBytes {
        _ = CC_SHA256($0, CC_LONG(data.count), &hash)
    }
    return Data(bytes: hash)
}

Update for Swift 5:

func sha256(data : Data) -> Data {
    var hash = [UInt8](repeating: 0,  count: Int(CC_SHA256_DIGEST_LENGTH))
    data.withUnsafeBytes {
        _ = CC_SHA256($0.baseAddress, CC_LONG(data.count), &hash)
    }
    return Data(hash)
}