“[String]”不能转换为“[NSString]”

Question

我正在关注此链接上的教程：http://www.raywenderlich.com/97014/use-cocoapods-with-swift

根据Xcode，有错误就行了

var components = (string as NSString).componentsSeparatedByString(",") as! [NSString]  

它说“[String]”不能转换为“[NSString]”。到底发生了什么，我应该如何解决？

谢谢！代码如下：

import UIKit

func RGB(red: CGFloat, green: CGFloat, blue: CGFloat) -> UIColor {
  return RGBA(red, green: green, blue: blue, alpha: 255)
}

func RGBA(red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) -> UIColor {
  return UIColor(red: red/255, green: green/255, blue: blue/255, alpha: alpha/255)
}

extension UIColor {

  class func RGBAColorFromString(string: String?) -> UIColor? {

    if let string = string {

      var components = (string as NSString).componentsSeparatedByString(",") as! [NSString]

      if components.count == 3 {
        components.append("1.0")
      }

      if components.count != 4 {
        return nil
      }

      let red = CGFloat(components[0].floatValue / 255)
      let green = CGFloat(components[1].floatValue / 255)
      let blue = CGFloat(components[2].floatValue / 255)
      let alpha = CGFloat(components[3].floatValue / 255)

      return UIColor(red: red, green: green, blue: blue, alpha: alpha)
    }

    return nil
  }
}

Answer 1

它使用以下语法：

var components = string.componentsSeparatedByString(",") as [NSString]