Swift OS X String to Int Conversion Error - string

Question

I'm having trouble converting a String to Int in my Swift OS X Xcode project. I have some data saved in a text file in a comma delimited format. The contents of the text file is below:
1,Cessna 172,3,54.4,124,38.6112
(and a line break at the end)
I read the text file and seperate it, first by \n to get each line by itself, and then by , to get each element by itself. The code to do this is below:
if let dir : NSString = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true).first {
let path = dir.stringByAppendingPathComponent("FSPassengers/aircraft.txt")
do {
let content = try NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding)
if content != "" {
let astrContent:[String] = content.componentsSeparatedByString("\n")
for aeroplane in astrContent {
let aSeperated:[String] = aeroplane.componentsSeparatedByString(",")
print(aSeperated[0])
print(Int(aSeperated[0]))
//self.aAircraft.append(Aircraft(id: aSeperated[0], type: aSeperated[1], passengerCapacity: Int(aSeperated[2])!, cargoCapacityKg: Double(aSeperated[3])!, cruiseSpeed: Int(aSeperated[4])!, fuelLitresPerHour: Double(aSeperated[5])!))
}
}
}
catch {
print("Error")
}
}
The end result here will be to assign each record (each line of the text file) into the array aAircraft. This array is made up of a custom object called Aircraft. The custom class is below:
class Aircraft: NSObject {
var id:Int = Int()
var type:String = String()
var passengerCapacity:Int = Int()
var cargoCapacityKg:Double = Double()
var cruiseSpeed:Int = Int()
var fuelLitresPerHour:Double = Double()
override init() {}
init(id:Int, type:String, passengerCapacity:Int, cargoCapacityKg:Double, cruiseSpeed:Int, fuelLitresPerHour:Double) {
self.id = id
self.type = type
self.passengerCapacity = passengerCapacity
self.cargoCapacityKg = cargoCapacityKg
self.cruiseSpeed = cruiseSpeed
self.fuelLitresPerHour = fuelLitresPerHour
}
}
In the first code extract above, where I split the text file contents and attempt to assign them into the array, you will see that I have commented out the append line. I have done this to get the application to compile, at the moment it is throwing me errors.
The error revolves around the conversion of the String values to Int and Double values as required. For example, Aircraft.id, or aSeperated[0] needs to be an Int. You can see that I use the line Int(aSeperated[0]) to convert the String to Int in order to assign it into the custom object. However, this line of code is failing.
The two print statements in the first code extract output the following values:
1
Optional(1)
If I add a ! to the end of the second print statement to make them:
print(aSeperated[0])
print(Int(aSeperated[0])!)
I get the following output:
I understand what the error means, that it tried to unwrap an optional value because I force unwrapped it, and it couldn't find an Int value within the string I passed to it, but I don't understand why I am getting the error. The string value is 1, which is very clearly an integer. What am I doing wrong?

Answer 1

Because Casena 172 is not convertible to an Int. You also have other decimal numbers which you will lose precision when casting them to Int. Use NSScanner to create an initializer from a CSV string:
init(csvString: String) {
let scanner = NSScanner(string: csvString)
var type: NSString?
scanner.scanInteger(&self.id)
scanner.scanLocation += 1
scanner.scanUpToString(",", intoString: &type)
self.type = type as! String
scanner.scanLocation += 1
scanner.scanInteger(&self.passengerCapacity)
scanner.scanLocation += 1
scanner.scanDouble(&self.cargoCapacityKg)
scanner.scanLocation += 1
scanner.scanInteger(&self.cruiseSpeed)
scanner.scanLocation += 1
scanner.scanDouble(&self.fuelLitresPerHour)
}
Usage:
let aircraft = Aircraft(csvString: "1,Cessna 172,3,54.4,124,38.6112")

Answer 2

As #mrkxbt mentioned, the issue was related to the blank line after the data in the text file. The string was being split at the \n which was assigning two values into the array. The first value was a string containing the data and the second was an empty string, so obviously the second set of splitting (by ,) was failing. Amended and working code is below:
if let dir : NSString = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true).first {
let path = dir.stringByAppendingPathComponent("FSPassengers/aircraft.txt")
do {
let content = try NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding)
if content != "" {
let astrContent:[String] = content.componentsSeparatedByString("\n")
for aeroplane in astrContent {
if aeroplane != "" {
let aSeperated:[String] = aeroplane.componentsSeparatedByString(",")
print(aSeperated[0])
print(Int(aSeperated[0])!)
self.aAircraft.append(Aircraft(id: Int(aSeperated[0])!, type: aSeperated[1], passengerCapacity: Int(aSeperated[2])!, cargoCapacityKg: Double(aSeperated[3])!, cruiseSpeed: Int(aSeperated[4])!, fuelLitresPerHour: Double(aSeperated[5])!))
}
}
}
}
catch {
print("Error")
}
}