Xcode 8.1 Swift 3 错误：无法将“String”类型的值转换为预期的参数类型“UnsafeMutableRawPointer”

Posted 2023-03-14

【中文标题】Xcode 8.1 Swift 3 错误：无法将“String”类型的值转换为预期的参数类型“UnsafeMutableRawPointer”

【英文标题】：Xcode 8.1 Swift 3 Error: cannot convert value of type 'String' to expected argument type 'UnsafeMutableRawPointer'

【发布时间】：2016-10-29 07:53:54

【问题描述】：

包含 var sceneData 代码的行给出了错误，显然是因为“路径”字符串。有谁知道如何解决这个问题？谢谢！

extension SKNode 
    class func unarchiveFromFile(_ file : String) -> SKNode? 
        if let path = Bundle.main.path(forResource: file, ofType: "sks") 
            var sceneData = Data(bytesNoCopy: path, count: .DataReadingMappedIfSafe, deallocator: nil)!
            var archiver = NSKeyedUnarchiver(forReadingWithData: sceneData)

            archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
            let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as! GameScene
            archiver.finishDecoding()
            return scene
         else 
            return nil
        
    

【参考方案1】：

Data(bytesNoCopy: 需要一个指针而不是字符串路径。

从磁盘读取Data 的API 是Data(contentsOf，但是它需要一个URL

extension SKNode 
  class func unarchiveFromFile(_ file : String) -> SKNode? 
    if let url = Bundle.main.url(forResource: file, withExtension: "sks") 
      do 
        var sceneData = try Data(contentsOf: url)
        var archiver = NSKeyedUnarchiver(forReadingWith: sceneData)

        archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
        let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as! GameScene
        archiver.finishDecoding()
        return scene
       catch 
        return nil
      
     else 
      return nil
    
  

在 Swift 3 中，我将方法重命名为

class func unarchive(from file : String) -> SKNode?  ...

【讨论】：

在 Swift 4 中，decodeObjectForKey 定义已更改为：let scene = archiver.decodeObject(forKey: NSKeyedArchiveRootObjectKey) as！游戏场景