在“super.init”调用之前在方法调用“foo”中使用“self”

Question

我正在使用来自 github 的这个开源项目：https://github.com/barnaclejive/FaceTrigger

我无法在子类中解决这个错误：

错误：在调用“super.init”之前，方法调用“onBoth”中使用了“self”

 class BrowDownEvaluator: BothEvaluator {

   func onBoth(delegate: FaceTriggerDelegate, newBoth: Bool) {
    delegate.onBrowDownDidChange?(browDown: newBoth)
    if newBoth {
        delegate.onBrowDown?()
    }
}

func onLeft(delegate: FaceTriggerDelegate, newLeft: Bool) {
}

func onRight(delegate: FaceTriggerDelegate, newRight: Bool) {
}

init(threshold: Float) {
    super.init(threshold: threshold, leftKey: .browDownLeft, rightKey: .browDownRight, onBoth: onBoth, onLeft: onLeft, onRight: onRight)
  }
}

父类：

  class BothEvaluator: FaceTriggerEvaluatorProtocol {

    private let threshold: Float
    private let leftKey: ARFaceAnchor.BlendShapeLocation
    private let rightKey: ARFaceAnchor.BlendShapeLocation
    private var onBoth: (FaceTriggerDelegate, Bool) -> Void
    private var onLeft: (FaceTriggerDelegate, Bool) -> Void
    private var onRight: (FaceTriggerDelegate, Bool) -> Void

    private var oldLeft  = false
    private var oldRight  = false
    private var oldBoth  = false

init(threshold: Float,
     leftKey: ARFaceAnchor.BlendShapeLocation ,
     rightKey: ARFaceAnchor.BlendShapeLocation ,
    onBoth: @escaping (FaceTriggerDelegate, Bool) -> Void,
    onLeft: @escaping (FaceTriggerDelegate, Bool) -> Void,
    onRight: @escaping (FaceTriggerDelegate, Bool) -> Void)
{
    self.threshold = threshold

    self.leftKey = leftKey
    self.rightKey = rightKey

    self.onBoth = onBoth
    self.onLeft = onLeft
    self.onRight = onRight
}

我知道我必须在这里初始化 onBoth 和其余方法但是您如何初始化该方法？我还在学习 Swift。

Answer 1

即使允许引用self.methodName，也不应将实例方法设置到实例属性中，这会产生引用循环。

一个简单的解决方法是这样的：

class BrowDownEvaluator: BothEvaluator {
    static func onBoth(delegate: FaceTriggerDelegate, newBoth: Bool) {
        delegate.onBrowDownDidChange?(browDown: newBoth)
        if newBoth {
            delegate.onBrowDown?()
        }
    }

    static func onLeft(delegate: FaceTriggerDelegate, newLeft: Bool) {
    }

    static func onRight(delegate: FaceTriggerDelegate, newRight: Bool) {
    }

    init(threshold: Float) {
        super.init(threshold: threshold, leftKey: .browDownLeft, rightKey: .browDownRight,
                   onBoth: BrowDownEvaluator.onBoth,
                   onLeft: BrowDownEvaluator.onLeft,
                   onRight: BrowDownEvaluator.onRight)
    }
}

如果您想以BrowDownEvaluator 的实例访问self，事情会变得有点复杂。