没有，不相容的cgaffinetransform

Question

我得到一个Nil与预期的参数类型不兼容＆＃39; unsafePointer＆＃39;此

的错误

let centerX = bounds.midX
    let centerY = bounds.midY

    let outerRadius = outerRadiusInRect(rect: bounds)
    let innerRadius = outerRadius - GNTickerButton.kOutterInnerRingSpacing

    let path = CGMutablePath()
    let padding = 8 as CGFloat

    CGPathAddArc(path, nil, centerX, centerY, GNTickerButton.kTearDropRadius,  CGFloat(2*M_PI),  CGFloat(M_PI), false)