如题，我想重写判断相等的方法，然后按照我的逻辑来进行去重。代码如下：

class Media: NSObject { var name = "" var serialNumber = "" init(name: String, serialNumber: String) { self.name = name self.serialNumber = serialNumber } override func isEqual(_ object: Any?) -> Bool { guard let other = object as? Media else { return false } return name == other.name && serialNumber == other.serialNumber } } func ==(lhs:Media, rhs: Media) -> Bool { return lhs.name == rhs.name && lhs.serialNumber == rhs.serialNumber } let media1 = Media(name: "Media1", serialNumber: "Serial1") let media2 = Media(name: "Media1", serialNumber: "Serial1") let media3 = Media(name: "Media2", serialNumber: "Serial1") let media4 = Media(name: "Media4", serialNumber: "Serial1") let set1 = Set(arrayLiteral: media1, media3) let set2 = Set(arrayLiteral: media2, media4) let newSet = set1.union(set2) print(newSet.count)

然后输出会有时是3，有时是4.这个我觉得特别奇怪。根据输出是通过isEqual方法来判断的，但是这个结果的不定性我不知道怎么办。

问题是，如何通过override的方式来控制【判断相等】的依据