swift 2.0 错误 : warning: could not load any Objective-C class information

Question

我收到这个错误:

warning: could not load any Objective-C class information

还有

Thread 1: EXC_BAD_ACCESS(code=2,address=0x7fff5588dfb8)

...分配此类时:

import UIKit
import QuartzCore


class CERangeSliderKnobLayer: CALayer {

    var highlighted = false
    weak var slider = CERangeSlider()

}

像这样的变量:

import UIKit

    class CERangeSlider: UIControl {

        /*
        // Only override drawRect: if you perform custom drawing.
        // An empty implementation adversely affects performance during animation.
        override func drawRect(rect: CGRect) {
            // Drawing code
        }
        */
        var maximumValue = CGFloat()
        var minimumValue = CGFloat()
        var upperValue = CGFloat()
        var lowerValue = CGFloat()

        var trackLayer = CERangeSliderKnobLayer()
        var upperKnobLayer = CERangeSliderKnobLayer()
        var lowerKnobLayer = CERangeSliderKnobLayer()

    ...
    }

这毫无意义。我所知道的项目中的任何地方都绝对没有 Objective C。都是 Swift。

更新

如果你不这样初始化它们而是像这样写它们，即

var trackLayer: CERangeSliderKnobLayer!

然后你得到一个错误:

fatal error: unexpectedly found nil while unwrapping an Optional value

类似的东西:

trackLayer.backgroundColor = UIColor.blueColor().CGColor

Answer 1

出于某种原因，答案是更改我的类，以便不初始化 weak 属性:

import QuartzCore


class CERangeSliderKnobLayer: CALayer {

    var highlighted = false
    weak var slider: CERangeSlider!

}