Swift indexOf, == operator override not getting called

I am getting frustrated with how Swift handles equality. Or I'm just missing something. How come these 2 indexOf DOESN'T work the same way?

let first = self.objects.indexOf(object) //This returns nil
let second = self.objects.indexOf{$0 == object} //This returns the index

My == override:

func ==(lhs: MyObject, rhs: MyObject) -> Bool {
    return lhs.someProperty == rhs.someProperty
}

The == override doesn't get called in the first indexOf. Why is that so? This feels really dangerous.

(MyObject is a subclass of PFObject (Parse.com objects). I don't know if this is what's messing this up.)

Since your Object is subclass of PFObject, and PFObject is subclass of NSObject, and NSObject already confirm to Equatable by using the isEqual method to implement. So your == operator override is not working. You should override the isEqual method. (To be honest, it's horrible :(

sample code:

class Object: NSObject {
    var value: Int
    init(value: Int) {
        self.value = value
    }

    override func isEqual(object: AnyObject?) -> Bool {
        guard let obj = object as? Object else { return false }
        return self.value == obj.value
    }
}

// If your class is not inherit from any ObjC class:
//extension Object: Equatable {}
//func ==(lhs: Object, rhs: Object) -> Bool {
//    return lhs.value == rhs.value
//}

let c = Object(value: 3)
let objs = [Object(value: 1), Object(value: 2), Object(value: 3)]

let index = objs.indexOf(c)
let index2 = objs.indexOf { $0 == c }
print(index) // Optional(2)
print(index2) // Optional(2)