Append 使用 Swift 将结构转换为数组（在 iOS 中失败，但在 Playgrounds 中失败）

Question

This is driving me crazy. This generic code creates an array of Structs and appends a new element, It runs fine in PlayGrounds or a macOS Command Line Tool project but. if you paste it to an iOS project (eg: inside your ViewController) it fails. it does not recognizes quiz as an array? Why. Help/Solution is appreciated. Thanks!

struct Question {
    let text: String
    let answer: String
    
    init(q: String, a: String){
        text = q
        answer = a
    }
}
    
var quiz = [
    Question(q: "A slug's blood is green.", a: "True"),
    Question(q: "Sky is blue", a: "True")
]

quiz.append(Question(q: "Ice is pink", a: "False")) //ERROR: Invalid redeclaration of 'quiz()'

Answer 1

Your quiz.append statement is not in any executable function, so it's like initializing a brand new instance of an object called "quiz", hence you get the "redeclaration" error.

In Playgrounds, I believe it executes the statements for you, like a script, so you're not required to put it in another method to be called at a later time.

Put the quiz.append statement in a func like so, and the error should go away:

func quizAppend(q: Question) {
  quiz.append(q)
}