Swift strings are not being stored in struct - swift

Question

I have a bare bones struct.
struct Transaction {
var value: String = ""
var date: String = ""
var title: String = ""
}
In my project, Transaction is used like so...
var transaction:Transaction = Transaction()
//loops 3 times
repeat {
let parsed = stringAndType(from:myParser)//-> (string:String, type:UInt8)
switch parsed.type {
case 1:
print("1 -- \(parsed.string")
transaction.value = parsed.string
case 2:
print("2 -- \(parsed.string)")
transaction.date = parsed.string
case 4:
print("4 -- \(parsed.string)")
transaction.title = parsed.string
default: break
}
} while myParser.isOk
print("Returning transaction: \(transaction)")
return transaction
In this code, a structure is created. The parser feeds the data to the switch, which assigns the parsed string to the appropriate Transaction variable. When I run the following code, the output indicates that the assignments to transaction.date and transaction.value are not sticking.
Output:
2 -- 12/22/2015
1 -- -5.00
4 -- RECURRING PAYMENT BACKBLAZE
Returning transaction: Transaction(value: "", date: "", title: "RECURRING PAYMENT BACKBLAZE")
There is complex buffering behind the scenes in stringAndType(). Looking at this as a C programmer, I really want to think that function might be the problem. However, I was under the impression that Swift strings are structures, and are therefore copy on write, just like an integer or double. Hoping you can provide insight. Thank you for your time.
Update 02/15/17
The logic in this code is functioning as expected. I think the problem here is memory management. To help drive this point, I've...
Removed the print lines from my switch
Added didSet {} to each variable in Transaction
Like so...
struct Transaction {
var value: String = "" {
didSet {
print("The VALUE has changed from \(oldValue) to \(value)")
}
}
//this is repeated appropriately for the other two variables
}
The given output rules out any logical issues. Output:
The DATE has changed from to 12/22/2015
The VALUE has changed from to -5.00
The TITLE has changed from to RECURRING PAYMENT BACKBLAZE
Returning transaction: Transaction(value: "", date: "", title: "RECURRING PAYMENT BACKBLAZE")
stringAndType() does read from an unsafe buffer, but it copies the bytes to a Data structure, and returns a string initialized from the COPIED data. I thought this would insulate me from safety issues...perhaps theres an implementation detail to String I'm missing?

Answer 1

Credit to #unkgd, you were on the right track with your initial answer before you retracted it. There was a logical error between the while parser.isOk loop and the parent loop (omitted to keep the code short) that was wiping Transaction between value and title being set. There was no indication of this happening in the output. The loop posted above was not looping three times, rather, it was looping once, but that single loop was iterated three times by the parent. Therefore, only the most recent parsed value was stored in the structure, in this case, title. Again, full credit to #unkgd (if you repost your answer and I will mark it as correct). Thanks to everyone for their ideas.