ios – 在Swift 1.2中将自身作为参数传递给init方法

以下类将’let’属性声明为隐式展开的变量.这之前适用于 Xcode 6.2：

class SubView: UIView {

    let pandGestureRecognizer: UIPanGestureRecognizer!

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.pandGestureRecognizer = UIPanGestureRecognizer(target: self,action: "panAction:")
    }

    func panAction(gesture: UIPanGestureRecognizer) {
        // ...
    }
}

更新到Xcode 6.3(使用Swift 1.2)后,会发生以下编译错误：

Property 'self.panGestureRecognizer' not initialized at super.init call
Immutable value 'self.panGestureRecognizer' may only be initialized once

在super.init调用之前移动以下行：

self.pandGestureRecognizer = UIPanGestureRecognizer(target: self,action: "panAction:")

给出以下错误：

'self' is used before super.init call

属性’panGestureRecognizer’不需要变异,因此必须将其声明为常量’let’.由于它是常量,因此必须在声明时具有初始值,或者在init方法中初始化它.要初始化它,需要在’target’参数中传递’self’.

其他线程建议将其声明为隐式解包可选,并在super.init调用后初始化它.这之前一直有效,直到我更新到Xcode 6.3.

有没有人知道这种情况的正确实施或

解决方法

？

let myOptional: Int?

if myCondition {
    myOptional = 1
} else {
    myOptional = nil
}

class SubView: UIView {
    let panGestureRecognizer = UIPanGestureRecognizer()

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

        panGestureRecognizer.addTarget(self,action: Selector("panAction:"))
    }
}