Swift String EXC_BAD_ACCESS

Question

我可能会遗漏一些非常简单的东西，但我无法理解为什么这段代码会给我这么多问题。

有时可行，但大部分时间都会抛出EXC_BAD_ACCESS Code = 1错误。内存地址也始终相同。

为tableview中的每个列调用此方法来创建自定义标头。初始化工作正常，只有在绘图时才会出现问题。 firstLine，secondLine，thirdLine似乎都已被释放。

class MultilineHeaderCell: NSTableHeaderCell {

private let firstLine: String
private let secondLine: String
private let thirdLine: String
private let horizontalPadding: CGFloat = 5.0
private var verticalPadding:CGFloat = 0.0
private var numberOfLines = 0
private var heightOfTextFrame:CGFloat = 0.0

init(HeaderText: String, PrimaryText: String, SecondaryText: String)
{        
    firstLine = HeaderText
    secondLine = PrimaryText
    thirdLine = SecondaryText

    super.init(textCell: "")
    let array = [firstLine, secondLine, thirdLine]
    for text in array {
        if text.isEmpty == false {
            numberOfLines++
            heightOfTextFrame = heightOfTextFrame + 21.0
        }
    }

}

convenience init(HeaderText: String)
{
    self.init(HeaderText: HeaderText, PrimaryText: "", SecondaryText: "")
}

convenience init(HeaderText: String, PrimaryText: String)
{
    self.init(HeaderText: HeaderText, PrimaryText: PrimaryText, SecondaryText: "")
}


required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}


override func drawWithFrame(cellFrame: NSRect, inView controlView: NSView) {

    verticalPadding = (cellFrame.height - heightOfTextFrame) / 2
    let textFrame = cellFrame.insetBy(dx: horizontalPadding, dy: verticalPadding)

    NSColor(calibratedRed: 217/255, green: 217/255, blue: 217/255, alpha: 1.0).set()      

    switch firstLine {
        case "Olivier" :
            NSColor(calibratedRed: 230/255, green: 184/255, blue: 184/255, alpha: 1.0).set()
        case "Lyttelton" :
            NSColor(calibratedRed: 216/255, green: 228/255, blue: 188/255, alpha: 1.0).set()
        case "Dorfman" :
            NSColor(calibratedRed: 184/255, green: 204/255, blue: 228/255, alpha: 1.0).set()
        case "Temporary Theatre" :
            NSColor(calibratedRed: 204/255, green: 198/255, blue: 218/255, alpha: 1.0).set()
        default :
            NSColor(calibratedRed: 217/255, green: 217/255, blue: 217/255, alpha: 1.0).set()
    }

    NSBezierPath(rect: cellFrame).fill()

    let paraStyle = NSParagraphStyle.defaultParagraphStyle().mutableCopy() as! NSMutableParagraphStyle
    paraStyle.alignment = .Center
    let font = NSFont.systemFontOfSize(11)
    let attributes = [NSForegroundColorAttributeName: NSColor.labelColor(), NSFontAttributeName: font, NSParagraphStyleAttributeName: paraStyle]
    let array = [firstLine, secondLine, thirdLine]

    switch numberOfLines {
    case 1:
        for (indexNumber, text) in array.enumerate() {
            if text.isEmpty == false {
                let yOffset = CGFloat(indexNumber * 21)
                text.drawCentredInRectWithYOffset(textFrame, attributes: attributes, yOffset: yOffset)
            }
        }
    case 2:
        for (indexNumber, text) in array.enumerate() {
            if text.isEmpty == false {
                let yOffset = CGFloat(indexNumber * 21)
                text.drawCentredInRectWithYOffset(textFrame, attributes: attributes, yOffset: yOffset)
            }
        }
    case 3:
        for (indexNumber, text) in array.enumerate() {
            if text.isEmpty == false {
                let yOffset = CGFloat(indexNumber * 21)
                text.drawCentredInRectWithYOffset(textFrame, attributes: attributes, yOffset: yOffset)
            }
        }
    default:
        print("NumberOfLines is wrong somehow!")
    }
}