Converting NSArray Contents to a varargs (With ARC) For Use With NSString initWithFormat

Question

We have some code today that takes an NSArray and passes it as a argument list to -[NSString initWithFormat:arguments] and we\'re trying to get this to work with ARC. Here\'s th

Answer 1

Cannot find a way to do this obj-c but a swift helper class finally got this working (my whole project is obj-c except this class)

@objc class StringFormat: NSObject {
    class func format(key: String, args: [AnyObject]) -> String {
        let locArgs: [CVarArgType] = args.map({ (arg: AnyObject) -> CVarArgType in
            if let iArg = (arg is NSNumber ? arg.intValue : nil) {
                return iArg
            }
            return arg as! CVarArgType
        });
        return String(format: key, arguments: locArgs)
    }
}

There is some magic going on, to do with how [CVarArgType] doesn't behave like a normal array - but this works in the flexible cross architecture way you expect it to.