Swift 2 to 3 conversion error with Value of type '[Any]' has no member - swift3

Question

I'm having a problem with a Swift 2 to 3 conversion piece of work and some of the remains syntax giving: Value of type '[Any]' has no member errors.
I was hoping someone could point me at a good solution.
Swift 2 code
Swift 2 code
func search() {
epsonPrinters = [Printer]()
starPrinters = [Printer]()
epson_startSearching()
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { [unowned self] in
let devices = SMPort.searchPrinter()
self.starPrinters = devices.map { portInfo -> Printer in
let p = Printer(
id: portInfo.modelName,
make: "Star Micronics",
model: portInfo.modelName,
portName: portInfo.portName)
if let name = portInfo.modelName as? String {
p.emulation = name.containsString("TSP143") ? "StarGraphics" : "StarLine"
}
return p
}
}
}
Swift 3 Code (I've added comments above areas with errors)
func search() {
epsonPrinters = [Printer]()
starPrinters = [Printer]()
epson_startSearching()
DispatchQueue.global(qos: .background).async { [unowned self] in
let devices = SMPort.searchPrinter()
self.starPrinters = [devices.map { portInfo -> Printer in
// id, model and portName in below fails with messages like:
// Value of type '[Any]' has no member 'modelName'
let p = Printer(
id: portInfo.modelName,
make: "Star Micronics",
model: portInfo.modelName,
portName: portInfo.portName)
// error on portInfo.modelName
// Value of type '[Any]' has no member 'modelName'
if let name = portInfo.modelName as? String {
p.emulation = name.containsString("TSP143") ? "StarGraphics" : "StarLine"
}
return p
}!]
}
}
I know that I can replace the 'id:...' part with the likes of:
id: ((portInfo[0] as AnyObject).modelName) ?? "",
But this isn't correct because PortInfo can have none, 1 or multiples depending on the number of printers we find.
I'd appreciate any suggestions for refactoring this in an elegant way that is good Swift 3 syntax and likely to survive into Swift 4.
I'm working in Xcode 8.3.2

Answer 1

When you get some errors about types, you'd better check what type each variable has. When you select devices in the line let devices = ..., Quick Help of Xcode will show you something like this:
Declaration let devices: [Any]?
First, it's an Optional and you need to unwrap it, before using the actual content.
Second, the type of the elements in devices is Any, to which you cannot apply any methods (including property accessors). You need to cast it to an appropriate type at an appropriate place.
To solve the two things above, you can write something like this:
guard let devices = SMPort.searchPrinter() as? [PortInfo] else {
fatalError("This may never happen")
}
With guard statement above, Quick Help will show you:
Declaration let devices: [PortInfo]
Non-Optional, simple Array of PortInfo, so you can use any methods of PortInfo for the elements of this devices.
I would translate your Swift 2 code into Swift 3 like this:
func search() {
epsonPrinters = []
starPrinters = []
epson_startSearching()
DispatchQueue.global(qos: .default).async {
guard let devices = SMPort.searchPrinter() as? [PortInfo] else {
fatalError("This may never happen")
}
self.starPrinters = devices.map { portInfo -> Printer in
let p = Printer(
id: portInfo.modelName,
make: "Star Micronics",
model: portInfo.modelName,
portName: portInfo.portName)
if let name = portInfo.modelName {
p.emulation = name.contains("TSP143") ? "StarGraphics" : "StarLine"
}
return p
}
}
}
You may need some fixes (not many, I believe) to use this code, as you are not showing all relevant things such as the definition of Printer.