How to access property or method from a variable? - ios

Question

Is it possible to access a method or property using a variable as the name of the method or property in Swift?
In PHP you can use $object->{$variable}. For example
class Object {
public $first_name;
}
$object = new Object();
$object->first_name = 'John Doe';
$variable = 'first_name';
$first_name = $object->{$variable}; // Here we can encapsulate the variable in {} to get the value first_name
print($first_name);
// Outputs "John Doe"
EDIT:
Here is the actual code I'm working with:
class Punchlist {
var nid: String?
var title: String?
init(nid: String) {
let (result, err) = SD.executeQuery("SELECT * FROM punchlists WHERE nid = \(nid)")
if err != nil {
println("Error")
}
else {
let keys = self.getKeys() // Get a list of all the class properties (in this case only returns array containing "nid" and "title")
for row in result { // Loop through each row of the query
for field in keys { // Loop through each property ("nid" and "title")
// field = "nid" or "title"
if let value: String = row[field]?.asString() {
// value = value pulled from column "nid" or "title" for this row
self.field = value //<---!! Error: 'Punchlist' does not have a member named 'field'
}
}
}
}
}
// Returns array of all class properties
func getKeys() -> Array<String> {
let mirror = reflect(self)
var keys = [String]()
for i in 0..<mirror.count {
let (name,_) = mirror[i]
keys.append(name)
}
return keys
}
}

Answer 1

You can do it, but not using "pure" Swift. The whole point of Swift (as a language) is to prevent that sort of dangerous dynamic property access. You'd have to use Cocoa's Key-Value Coding feature:
self.setValue(value, forKey:field)
Very handy, and it crosses exactly the string-to-property-name bridge that you want to cross, but beware: here be dragons.
(But it would be better, if possible, to reimplement your architecture as a dictionary. A dictionary has arbitrary string keys and corresponding values, and thus there is no bridge to cross.)

Answer 2

Subscripting may help you.
let punch = Punchlist()
punch["nid"] = "123"
println(punch["nid"])
class Punchlist {
var nid: String?
var title: String?
subscript(key: String) -> String? {
get {
if key == "nid" {
return nid
} else if key == "title" {
return title
}
return nil
}
set {
if key == "nid" {
nid = newValue
} else if key == "title" {
title = newValue
}
}
}
}