带常量和作用域的Swift可选绑定

Question

I'm trying to understand why the following is valid in Swift. I'm assuming it has to do with the way things are scoped in Swift.

let name = "test" //assigns "test" to name
var optionalName: String? = "John Appleseed"
var greeting = "Hello!"
if let name = optionalName { //assigns "John Appleseed" to name
  let name = "no error" //assigns "no error" to name
  greeting = "Hello, \(name)" //assigns "Hello, no error" to greeting
}
println(name) //prints "test"

What I believe is happening is this is creating 3 separate name constants all in different scopes. The first let name is in the global scope. Then the optional binding let name is another scope, and then within the if the let name is another scope. Then the final print goes back out to the global scope.

Answer 1

您已经了解：)它使用找到的第一个具有该名称的变量，从内部范围开始向上。