swift - 为 UIColor 创建自定义颜色

Question

我有一个关于在 swift 中创建自定义 UIColor 的问题。

我使用了以下扩展代码:

import UIKit

extension UIColor {
  convenience init(red: Int, green: Int, blue: Int) {
    let newRed = CGFloat(red)/255
    let newGreen = CGFloat(green)/255
    let newBlue = CGFloat(blue)/255

    self.init(red: newRed, green: newGreen, blue: newBlue, alpha: 1.0)


    }
}

let brandBlue = UIColor(red: 0, green: 127, blue: 255)

我想将其加载到shadowColor中，使用以下代码:

class squareButton : UIButton {

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.layer.cornerRadius = 10.0
        self.layer.shadowColor = (Loading code here)
        self.layer.shadowRadius = 1.5
        self.layer.shadowOffset = CGSize(width: 0.0, height: 2.0)
        self.layer.shadowOpacity = 0.6
        self.layer.masksToBounds = false   
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.layer.cornerRadius = 10.0
        self.layer.shadowColor = (Loading code here)
        self.layer.shadowRadius = 1.5
        self.layer.shadowOffset = CGSize(width: 0.0, height: 2.0)
        self.layer.shadowOpacity = 0.6
        self.layer.masksToBounds = false  
    }
}

但是我使用的每个组合都不起作用。每次它都说我应该使用as! CGColor，但是当我这样做时，应用程序崩溃了。

请帮助我

谢谢

Answer 1

在您的代码中，您当前正在向 self.layer.shadowColor = (Loading code here) 提供 UIColor，这应该会导致编译器错误。

您创建的扩展没问题。在实例化新的 UIColor 实例后，只需使用 UIColor 的 .cgColor 属性即可。这将是示例代码:

class SquareButton: UIButton {

    let brandBlue: UIColor = UIColor(red: 0, green: 127, blue: 255)

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.layer.cornerRadius = 10.0
        self.layer.shadowColor = brandBlue.cgColor
        self.layer.shadowRadius = 1.5
        self.layer.shadowOffset = CGSize(width: 0.0, height: 2.0)
        self.layer.shadowOpacity = 0.6
        self.layer.masksToBounds = false   
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.layer.cornerRadius = 10.0
        self.layer.shadowColor = brandBlue.cgColor
        self.layer.shadowRadius = 1.5
        self.layer.shadowOffset = CGSize(width: 0.0, height: 2.0)
        self.layer.shadowOpacity = 0.6
        self.layer.masksToBounds = false  
    }
}