xcode - 失败的初始化程序'init(fileURL :) cannot override a non-failable initializer

Question

我不确定如何在 Xcode 6.4 中修复此错误

override init?(fileURL url: NSURL) {
    super.init(fileURL: url)

    let center = NSNotificationCenter.defaultCenter()
    center.addObserver(self, selector: "thingsDidChange:", name: WhatsitDidChangeNotification, object: nil)
}

deinit {
    let center = NSNotificationCenter.defaultCenter()
    center.removeObserver(self)
}

Answer 1

您的 init?(_:) 函数中没有任何内容可能会失败并强制您返回 nil。只需删除 init 签名末尾的问号即可。

override init(fileURL url: NSURL) {
    super.init(fileURL: url)
    let center = NSNotificationCenter.defaultCenter()
    center.addObserver(self, selector: "thingsDidChange:", name: WhatsitDidChangeNotification, object: nil)
}