StringNumberFormatter.swift

/*
I was doing a migration from Swift 2.3 to 3.0.1. When I encountered a String extension that converts a string number,
gives it a format, then returns the formatted string number.

The problem was, I changed to a NumberFormatter instance but the instance method asked me for a NSNumber.
I came with a solution and while it doesn't work for every value, it works for my use.
*/

// Old implementation
extension String {
    public func formatNumber() -> String
    {
        let numerFormatter = NSNumberFormatter()
        numerFormatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
        return numerFormatter.stringFromNumber(Int(self)!)!
    }
}

// New implementation
// I had two options
// I went with option 2. Because I just can't risk the Int(self) to fail. 

// Option 1
extension String {
    public func formatNumber() -> String {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        let nsnumber = NSNumber(integerLiteral: Int(self)!)
        return formatter.string(from: nsnumber) ?? ""
    }
}

// Option 2
extension String {
    public func formatNumber() -> String {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        if let number = Int(self) {
            let nsnumber = NSNumber(value: number)
            return formatter.string(from: nsnumber) ?? ""
        } else {
            print("Couldn't cast Int(self) at \(#function)")
            return ""
        }
    }
}