ios - 如何在 Swift 中对对象进行 Nil

Question

如何在 Swift 中将 nil 赋值给一个对象。如果直接分配，我会收到错误消息。

Answer 1

From Apple Documentation:

nil cannot be used with nonoptional constants and variables. If a constant or variable in your code needs to work with the absence of a value under certain conditions, always declare it as an optional value of the appropriate type

同样重要的是要注意:

Swift’s nil is not the same as nil in Objective-C. In Objective-C, nil is a pointer to a nonexistent object. In Swift, nil is not a pointer—it is the absence of a value of a certain type. Optionals of any type can be set to nil, not just object types

希望对你有帮助!