Objective-C 到 Swift 的翻译问题

Question

我正在尝试将这一行简单的代码转换为 Swift，但不知道如何编写:

AVCaptureConnection *videoConnection = nil;

我试过:

    let videoConnection: AVCaptureConnection = nil

    let videoConnection: AVCaptureConnection = false

    var videoConnection:AVCaptureConnection = AVCaptureConnection()
            videoConnection = nil

    var videoConnection:AVCaptureConnection = AVCaptureConnection()
            videoConnection = false

var videoConnection:AVCaptureConnection = AVCaptureConnection()
            videoConnection.active = false

var videoConnection:AVCaptureConnection = AVCaptureConnection()
            videoConnection.active = nil

任何关于如何编写 Swift 的建议都将不胜感激。

Answer 1

如果你想用 nil “初始化”某些东西，它必须是一个可选的。所以

var videoConnection: AVCaptureConnection? = nil

或

var videoConnection: AVCaptureConnection?

会是对的。