Compare two instances of an object in Swift - class

Question

Given the following class, how can all the values in two instances be compared to each other?
// Client Object
//
class PLClient {
var name = String()
var id = String()
var email = String()
var mobile = String()
var companyId = String()
var companyName = String()
convenience init (copyFrom: PLClient) {
self.init()
self.name = copyFrom.name
self.email = copyFrom.email
self.mobile = copyFrom.mobile
self.companyId = copyFrom.companyId
self.companyName = copyFrom.companyName
}
}
var clientOne = PLClient()
var clientTwo = PLClient(copyFrom: clientOne)
if clientOne == clientTwo { // Binary operator "==" cannot be applied to two PLClient operands
println("No changes made")
} else {
println("Changes made. Updating server.")
}
The use-case for this is in an application which presents data from a server. Once the data is converted into an object, a copy of the object is made. The user is able to edit various fields etc.. which changes the values in one of the objects.
The main object, which may have been updated, needs to be compared to the copy of that object. If the objects are equal (the values of all properties are the same) then nothing happens. If any of the values are not equal then the application submits the changes to the server.
As is shown in the code sample, the == operator is not accepted because a value is not specified. Using === will not achieve the desired result because these will always be two separate instances.

Answer 1

Indicate that your class conforms to the Equatable protocol, and then implement the == operator.
Something like this:
class PLClient: Equatable
{
var name = String()
var id = String()
var email = String()
var mobile = String()
var companyId = String()
var companyName = String()
//The rest of your class code goes here
public static func ==(lhs: PLClient, rhs: PLClient) -> Bool{
return
lhs.name == rhs.name &&
lhs.id == rhs.id &&
lhs.email == rhs.email &&
lhs.mobile == rhs.mobile &&
lhs.companyId == rhs.companyId &&
lhs.companyName == rhs.companyName
}
}

Answer 2

Working off of Duncan C's answer, I have come up with an alternative which is slightly clearer that it is being used in a custom way:
// Client Object
//
class PLClient {
var name = String()
var id = String()
var email = String()
var mobile = String()
var companyId = String()
var companyName = String()
convenience init (copyFrom: PLClient) {
self.init()
self.name = copyFrom.name
self.email = copyFrom.email
self.mobile = copyFrom.mobile
self.companyId = copyFrom.companyId
self.companyName = copyFrom.companyName
}
func equals (compareTo:PLClient) -> Bool {
return
self.name == compareTo.name &&
self.email == compareTo.email &&
self.mobile == compareTo.mobile
}
}
var clientOne = PLClient()
var clientTwo = PLClient(copyFrom: clientOne)
if clientOne.equals(clientTwo) {
println("No changes made")
} else {
println("Changes made. Updating server.")
}

Answer 3

You could loop through fields by using keypath
I haven't tested this, but the general idea is there. Give a list of valid fields and loop through them instead of writing every single equatable. So it's the same as #duncan-c suggested but with looping.
Something like:
class PLClient:Equatable {
var name = String()
var id = String()
var email = String()
var mobile = String()
var companyId = String()
var companyName = String()
public static func ==(lhs: PLClient, rhs: PLClient) -> Bool{
let keys:[KeyPath<PLClient, String>] = [\.name, \.id, \.email, \.mobile, \.companyId, \.companyName]
return keys.allSatisfy { lhs[keyPath: $0] == rhs[keyPath: $0] }
}
}

Answer 4

Try "is" keyword in swift,
e.g.
if self.navigationController.topViewController is TestViewController {
//Logic here
}