iOS Locksmith cannot move stored data to from service "A" to service "B"

Question

In one of my iOS apps I'm developing I'm storing some info in the Keychain. To interact with the keychain I am using Locksmith (https://github.com/matthewpalmer/Locksmith)

In version v1 of my app, I was writing some data in the keychain by using

Locksmith.saveData(data: data, forUserAccount:"A1", inService: "S1")

Now, in v2, I realized that I would like to migrate my data from "S1" to "S2", so I've set on to writing a small migration script to achieve this.

Essentially, what I am doing:

// read the old data
if let d = Locksmith.loadDataForUserAccount(userAccount: "A1", inService: "S1") {

   // write it in a new location
   Locksmith.saveData(data: d, forUserAccount: "A1", inService: "S2")
}

This is an oversimplification of my code.

The problem is that d = nil every time, although I know for sure it exists (when I am building the v1 of the app, I can see the data exists in that location).

Any ideas on this? Did somebody run into this problem before?

Some tech specs:

• Xcode 8.3
• Swift 3.1
• Locksmith 3.0 (via Carthage)
• iOS Simulator (iPhone 6s) running iOS 10.3

Didn't try on a real device.