Crashalot Crashalot - 6 months ago 29
Swift Question

Overridden == function for Equatable type not called for custom class that subclasses NSCoding and NSObject

The

FooBar
class below has to override the
==
function of the
Equatable
type.

However, calling
contains
on an array of
FooBar
objects does not cause a breakpoint inside the custom
==
function to get invoked. Is it possible another
==
function is overriding this custom one?

Note: Because FooBar must subclass from NSCoding and NSObject, FooBar does not list Equatable as a protocol because it causes this error:


Redundant conformance of 'FooBar' to protocol 'Equatable'


func ==(lhs: FooBar, rhs: FooBar) -> Bool {
return lhs.id == rhs.id
}

class FooBar: NSObject, NSCoding {
// Class def
}

// Both serverFooBars and gFooBars are [FooBar]
let newFooBars = serverFooBars.filter { !gFooBars.contains($0) }

Answer

Because your class inherits from NSObject you do not need to use the swift protocol Equatable instead you must override the NSObject method isEquals:

class FooBar: NSObject, NSCoding {
  override func isEqual(object: AnyObject?) -> Bool {
    return id == (object as? FooBar)?.id
  }
}
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