Convert Array of [[Double]] to String (similar to Print() output)

let intervals = [[1,1],[2,2],[3,3]]

I would like to store this intervals variables into CloudKit as String in the same form as a print output eg:

print(interval)

output = [[1,1],[2,2],[3,3]]

How can this be achieved? All the solutions from SO and googling only led me to doing a join whereby the arrays would be lost eg: [1,1,2,2,3,3]

>Solution :

You can try

let intervals = [[1,1],[2,2],[3,3]] 
let res = "[\(intervals.map { "[\($0.first!),\($0.last!)]" }.joined(separator: ","))]" 
print(res)

OR

let res =  String(data: try! JSONEncoder().encode(intervals), encoding: .utf8)!

OR

let res = String(describing: intervals)