ios - Xcode Swift - 检测屏幕上颜色的触摸

Question

我正在使用带有 Swift 的 Xcode 6 Beta，我想创建一个方法，当屏幕上的手指触摸特定的 UIColour(例如灰色)时调用该方法。

我该怎么做？

Answer 1

Objective-C 已经回答了这个问题.该代码在 Swift 中略有不同，但我还是对其进行了转换；

extension UIView
{
    func colorOfPoint (point: CGPoint) -> UIColor
    {
        var pixel = UnsafePointer<CUnsignedChar>.alloc(4)
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let bitmapInfo = CGBitmapInfo.fromRaw(CGImageAlphaInfo.PremultipliedLast.toRaw())!
        let context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, bitmapInfo)

        CGContextTranslateCTM(context, -point.x, -point.y)

        self.layer.renderInContext(context)

        CGContextRelease(context)
        CGColorSpaceRelease(colorSpace)

        return UIColor(red: Float(pixel [0]) / 255.0, green: Float (pixel [1]) / 255.0, blue: Float (pixel [2]) / 255.0 , alpha: Float (pixel [3]) / 255.0)
    }
}

在你的 View Controller 中；

override func touchesBegan(touches: NSSet!, withEvent event: UIEvent!)
{
    let touch : UITouch = event.allTouches().anyObject() as UITouch
    let location = touch.locationInView(self.view)
    pickedColor = self.view.colorOfPoint (location)
    // Do something with picked color.
}