if someObject === nil {
    }

您必须使用==操作符进行测试,例如

if someObject == nil {
    }

我以为===更像是确保完全相同(基本上比较指针)和==的实例更像isEqual检查.因此,我会认为===将更适合测试对零,但我显然不正确.

文件规定：

=== or “Identical to” means that two constants or variables of class type
refer to exactly the same class instance.

== or “Equal to” means that two instances are considered “equal” or “equivalent”
in value,for some appropriate meaning of “equal”,as defined by the type’s designer.”

var s: String? = nil
s === nil // true