Array.contains returns false - ios

Question

I have an array of users [User] called conversationUsers
User is defined as
public class User: NSManagedObject { ... }
and currUser is an User object
if I try
currUser == conversationUsers[0]
it results true
but
conversationUsers.contains(currUser)
results false
If instead I use
conversationUsers.contains({$0 == currUser})
it returns true
FYI I have also defined this:
public func ==(lhs: User, rhs: User) -> Bool {
let logicalExpression = lhs.email.lowercaseString == rhs.email.lowercaseString
return logicalExpression
}
Why contains returns false? Which is his default predicate?
Thank you for your help

Answer 1

UPDATE
In short, you should override NSObject.isEqual() method:
public class User: NSManagedObject {
...
override func isEqual(object: AnyObject?) -> Bool {
if let rhs = object as? User {
return self == rhs
}
return false
}
}
I made a little research. It seems that if class A is inherited from NSObject then collection methods like contains use NSObject.isEqual() method for determining equality of two objects. Class B is not inherited from NSObject so contains method is working as expected.
import Foundation
class A: NSObject {
var value: Int
init(_ value: Int) {
self.value = value
}
}
func ==(lhs: A, rhs: A) -> Bool {
return lhs.value == rhs.value
}
var a = A(1)
var array: [A] = [a, A(2)]
array.contains(a) // true
array.contains(A(1)) // false
array.contains { $0 == A(1) } // true
array[0] == A(1) // true
class B: Equatable {
var value: Int
init(_ value: Int) {
self.value = value
}
}
func ==(lhs: B, rhs: B) -> Bool {
return lhs.value == rhs.value
}
var b = B(1)
var array2: [B] = [b, B(2)]
array2.contains(b) // true
array2.contains(B(1)) // true
array2.contains { $0 == B(1) } // true
array2[0] == B(1) // true
So you need to override NSObject.isEqual() method:
class A: NSObject {
var value: Int
init(_ value: Int) {
self.value = value
}
override func isEqual(object: AnyObject?) -> Bool {
if let rhs = object as? A {
return self == rhs
}
return false
}
}
OLD ANSWER
User class should also conform to Equatable protocol:
extension User: Equatable {}
Or you can add it directly to class definition:
public class User: NSManagedObject, Equatable {}