Swift 4中键值编码的优点

Question

I just want to know the benefits of Key-Value Coding in Swift 4. As I am well aware of key-value coding (hold reference to properties without actually accessing the underlying data held by the property).

For Example:

struct Student {
    var name: String?
    var rollNo: String?
}

let student = Student(name: "aman", rollNo: "12121")
let nameKey = \Student.name
let name = student[keyPath: nameKey]

Here we created the the instance of Student and access the value by subscript (keyPath) but I can easily access the value by simply writing the code student.name .

In Objective-C, we use string as a key like given below and we could take some benefits from it

 [object valueForKey:@"name"]

My question is that is there any benefits related to coding level or memory level?

Answer 1

Two key advantages are:

1. Keys are validated: Xcode will warn you, at compile time, if you try to use a key that is not valid.

2. Results are strongly typed: With the following, the compiler will know that the resulting name is a String :

    let name = student[keyPath: nameKey] 

   This eliminates the need to do any casting.

The result is that it's much easier to write safe code.