ios - 在 Init 函数外初始化类属性

Question

抱歉，如果这是一个基本问题，但我无法在任何地方找到解决方案。我想在 Init 之外的函数中初始化类属性，并且只从构造函数内部调用它。我这样做是为了避免代码重复，因为当前版本如下所示:

public class WifiNameDisplay: UIView {
    var wifiImageView: UIImageView
    var networkName: UILabel
    public var networkSSID: String {
        didSet {
            networkName.text = networkSSID
            adjustSizeToContent()
        }
    }

    override public init(frame: CGRect) {
        networkSSID = "NETWORK"
        wifiImageView = UIImageView(image: UIImage(named: "wifi_icon.png")!)
        networkName = UILabel(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: 400, height: wifiImageView.frame.size.height)))

        super.init(frame: frame)
    }


    convenience public init() {
        self.init(frame: CGRect.zero)
    }

    required public init(coder aDecoder: NSCoder) {
        networkSSID = "NETWORK"
        wifiImageView = UIImageView(image: UIImage(named: "wifi_icon.png")!)
        networkName = UILabel(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: 400, height: wifiImageView.frame.size.height)))

        super.init(coder: aDecoder)!
    }
}

我想把它改成这样:

public class WifiNameDisplay: UIView {
    var wifiImageView: UIImageView
    var networkName: UILabel
    public var networkSSID: String {
        didSet {
            networkName.text = networkSSID
            adjustSizeToContent()
        }
    }

    override public init(frame: CGRect) {
        initDefaultValues()
        super.init(frame: frame)
    }


    convenience public init() {
        self.init(frame: CGRect.zero)
    }

    required public init(coder aDecoder: NSCoder) {
        initDefaultValues()
        super.init(coder: aDecoder)!
    }

    func initDefaultValues() {
        networkSSID = "NETWORK"
        wifiImageView = UIImageView(image: UIImage(named: "wifi_icon.png")!)
        networkName = UILabel(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: 400, height: wifiImageView.frame.size.height)))
    }
}

问题是编译器不允许这样做，调用“在 super.init 初始化 self 之前在方法调用‘initDefaultValues’中使用‘self’”。我想要的是可能的，还是我被迫使用重复代码？

Answer 1

如果您将属性声明为隐式展开的可选值，那么您可以在调用父类(super class)初始化函数后初始化它们 -

public class WifiNameDisplay: UIView {
    var wifiImageView: UIImageView!
    var networkName: UILabel!
    public var networkSSID: String! {
        didSet {
            networkName.text = networkSSID
          //  adjustSizeToContent()
        }
    }

    override public init(frame: CGRect) {

        super.init(frame: frame)
        initDefaultValues()
    }


    convenience public init() {
        self.init(frame: CGRect.zero)
    }

    required public init(coder aDecoder: NSCoder) {

        super.init(coder: aDecoder)!
        initDefaultValues()
    }

    func initDefaultValues() {
        networkSSID = "NETWORK"
        wifiImageView = UIImageView(image: UIImage(named: "wifi_icon.png")!)
        networkName = UILabel(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: 400, height: wifiImageView.frame.size.height)))
    }
}