Memory.swift

class Object { }

var a: Object? = Object()
weak var weakA = a
a = nil
print(a ?? "nil")
print(weakA ?? "nil")

print("-------------------------------------------------")

var b: Object?
b = Object()
weak var weakB = b
b = nil
print(b ?? "nil")
print(weakB ?? "nil")

The console output is

nil
nil
-------------------------------------------------
nil
__lldb_expr_33.Object