「[字符串]」不是轉換爲「[的NSString]」

Question

我下面這個鏈接教程：http://www.raywenderlich.com/97014/use-cocoapods-with-swift

據Xcode中，有上線的錯誤

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

它說'[String]'不能轉換爲'[NSString]'。到底發生了什麼，我該如何解決？

謝謝！下面是代碼：

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

它的工作原理與此語法：

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