Swift - array to data and back to string

Question

I want to array string to base64 and then back to the string

I try the following

let array = [[1,2,"preved"], [3,4,"hola"], [5,6,"poka"]]

let encodedData = NSKeyedArchiver.archivedData(withRootObject: array)

let base64String = encodedData.base64EncodedString()

let data = Data(base64Encoded: base64String)
let decodedData = NSString(data: data!, encoding: String.Encoding.utf8.rawValue)
print(decodedData)

problem is that decoded data prints back nil

What am I doing wrong ?

You are missing the reverse of NSKeyedArchiver => NSKeyedUnarchiverArchiver. — Larme
– Larme, Commented Jul 24, 2017 at 12:21
It is returning nil because you are base64 encoding the data from NSString but trying to construct it back using normal NSString initialiser. To get back the string use data!.base64EncodedString() — firstinq
– firstinq, Commented Jul 24, 2017 at 12:30
Replace create decodedData from NSString to if let data = Data(base64Encoded: base64String) { let decodedData = NSKeyedUnarchiver.unarchiveObject(with: data) print(decodedData) } — sehaswaran
– sehaswaran, Commented Jul 24, 2017 at 12:58

Ahmad F · Accepted Answer · 2017-07-24 12:53:02Z

When using NSKeyedArchivercoder , NSKeyedUnarchiver decoder should be also used:

NSKeyedArchiver, a concrete subclass of NSCoder, provides a way to encode objects (and scalar values) into an architecture-independent format that can be stored in a file. When you archive a set of objects, the class information and instance variables for each object are written to the archive. The companion class NSKeyedUnarchiver decodes the data in an archive and creates a set of objects equivalent to the original set.

-In the simplest way- as follows:

let array = [[1,2,"preved"], [3,4,"hola"], [5,6,"poka"]]

let encodedData = NSKeyedArchiver.archivedData(withRootObject: array)

if let decodedArray = NSKeyedUnarchiver.unarchiveObject(with: encodedData) as? [Any] {
    // ...
}

Note that since array data type is [Array<Any>], you should cast it as [Any]

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