得到错误：EXC_BAD_INSTRUCTION（代码= EXC_I386_INVOP，子代码= 0x0），为什么？

Question

我的代码如下：

let mvc = MainViewController()
    let average = mvc.defaults.array(forKey: "grades") as! [Int]
    let averagePoints = mvc.defaults.integer(forKey: "averagePoints")
    gradePoints = averagePoints/average.count

在最后一行，我收到一个EXC_BAD_INSTRUCTION（代码= EXC_I386_INVOP，子代码= 0x0）错误。这意味着什么，为什么我会得到它？

感谢您的帮助！

Answer 1

试试这个：

if let average = mvc.defaults.array(forKey: "grades") as? [Int],
    let averagePoints = mvc.defaults.integer(forKey: "averagePoints") {
    gradePoints = averagePoints/average.count
}

似乎grades数组或/和averagePoints是/是。