swift - 如何快速将 COpaquePointer 转换为某种类型(特别是 CGContext？)

Question

我有以下无法编译的 swift 代码:

class CustomView: NSView {
  override func drawRect(dirtyRect: NSRect) {
    var contextPointer: COpaquePointer = NSGraphicsContext.currentContext()!.graphicsPort()
    var context: CGContext? = contextPointer as? CGContext
    CGContextSetRGBFillColor(context, 1, 0, 0, 1)
    CGContextFillRect(context, CGRectMake(0, 0, 100, 100))
    CGContextFlush(context)
  }
}

如何将 COpaquePointer 转换为 CGContext？

Answer 1

从 Developer Preview 5 开始，NSGraphicsContext 现在有一个 CGContext 属性。它尚未记录在案，但它在头文件中:

@property (readonly) CGContextRef CGContext NS_RETURNS_INNER_POINTER NS_AVAILABLE_MAC(10_10);