Swift 等效于 Objective-C FourCharCode 单引号文字(例如“TEXT") [英] Swift equivalent to Objective-C FourCharCode single quote literals (e.g. 'TEXT')

问题描述

我正在尝试在 Swift 中复制一些 Objective C 可可.一切都很好，直到我遇到以下情况:

I am trying replicate some Objective C cocoa in Swift. All is good until I come across the following:

// Set a new type and creator:
unsigned long type = 'TEXT';
unsigned long creator = 'pdos';

如何从这样的单引号字符文字创建 Int64(或正确的 Swift 等效项)?

How can I create Int64s (or the correct Swift equivalent) from single quote character literals like this?

类型:

public typealias AEKeyword = FourCharCode
public typealias OSType = FourCharCode
public typealias FourCharCode = UInt32

推荐答案

我在我的 Cocoa Scripting 应用程序中使用它，它正确地考虑字符 > 0x80

I'm using this in my Cocoa Scripting apps, it considers characters > 0x80 correctly

func OSTypeFrom(string : String) -> UInt {
  var result : UInt = 0
  if let data = string.dataUsingEncoding(NSMacOSRomanStringEncoding) {
    let bytes = UnsafePointer<UInt8>(data.bytes)
    for i in 0..<data.length {
      result = result << 8 + UInt(bytes[i])
    }
  }
  return result
}

替代

func fourCharCodeFrom(string : String) -> FourCharCode
{
  assert(string.count == 4, "String length must be 4")
  var result : FourCharCode = 0
  for char in string.utf16 {
    result = (result << 8) + FourCharCode(char)
  }
  return result
}

或者仍然更快

func fourCharCode(from string : String) -> FourCharCode
{
  return string.utf16.reduce(0, {$0 << 8 + FourCharCode($1)})
}

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