失败的初始值设定项'init（fileURL :)无法覆盖非失败的初始值设定项

Question

I am not sure how to fix this error in Xcode 6.4

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

There is nothing in your init?(_:) function that can fail and force you to return nil . Simply remove the trailing question mark of the init signature.

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