UIColor组件

Question

我试图提取UIColor对象的组件，并有以下代码：

    var red1:CGFloat = 0
    var green1:CGFloat = 0
    var blue1:CGFloat = 0
    var alpha1:CGFloat = 0

    var red2:CGFloat = 0
    var green2:CGFloat = 0
    var blue2:CGFloat = 0
    var alpha2:CGFloat = 0

    var bool1 = color1.getRed(&red1, green: &green1, blue: &blue1, alpha: &alpha1)
    var bool2 = color2.getRed(&red2, green: &green2, blue: &blue2, alpha: &alpha2)

    var components = CGColorGetComponents(color1.CGColor)
    NSLog("Color1 Components Method: %f, %f, %f, %f", components[0], components[1], components[2], components[3])

    NSLog((bool1 == true) ? "YES" : "NO")
    NSLog((bool2 == true) ? "YES" : "NO")

    var alpha:CGFloat = (1 - (1 - alpha1) * (1 - alpha2))
    if (alpha < 1.0e-6) {
        return UIColor.clearColor()
    }

    NSLog("Color1: %@", color1)
    NSLog("%f, %f, %f %f", red1, green1, blue1, alpha1)

    NSLog("Color2: %@", color2)
    NSLog("%f, %f, %f %f", red2, green2, blue2, alpha2)

但是，所有组件的计算值都为零，我不知道为什么。这是输出：

   2014-09-22 21:03:22.923 Colors[46574:589980] Color1 Components Method: 0.000000,    0.000000, 0.000000, 0.000000
   2014-09-22 21:03:22.923 Colors[46574:589980] YES
   2014-09-22 21:03:22.923 Colors[46574:589980] YES
   2014-09-22 21:03:22.924 Colors[46574:589980] Color1: UIDeviceRGBColorSpace 1 0 0 1
   2014-09-22 21:03:22.924 Colors[46574:589980] 0.000000, 0.000000, 0.000000 0.000000
   2014-09-22 21:03:22.924 Colors[46574:589980] Color2: UIDeviceRGBColorSpace 0 0 1 1
   2014-09-22 21:03:22.924 Colors[46574:589980] 0.000000, 0.000000, 0.000000 0.000000

有人能告诉我我在这里做错了什么吗？

Answer 1

值不是零，它们只是那样打印，因为您要将CGFloat打印为Float。要解决这个问题：

NSLog("%f, %f, %f, %f", Float(red1), Float(green1), Float(blue1), Float(alpha1))

或

NSLog("%@, %@, %@, %@", red1, green1, blue1, alpha1)

或

println("\(red1), \(green1), \(blue1), \(alpha1)")