sakiweiblog-rewrite-objective-c-file-reader-to-swift-swift-extension.swift

extension NSData {
  
  func rangeOfData_dd(dataToFind: NSData) -> NSRange {
    let bytes = self.bytes
    let len = self.length
    
    let searchBytes = dataToFind.bytes
    let searchLen = dataToFind.length
    var searchIndex = 0
    
    var foundRange = NSMakeRange(NSNotFound, searchLen)
    
    // 1.
    for i in 0..<len {
    
      // 2.
      if UnsafePointer<CChar>(bytes)[i] == UnsafePointer<CChar>(searchBytes)[searchIndex] {
        if foundRange.location == NSNotFound {
          foundRange.location = i
        }
        searchIndex += 1
        if searchIndex >= searchLen {
          return foundRange
        }
      } else {
        searchIndex = 0
        foundRange.location = NSNotFound
      }
    }
    
    return foundRange
  }
}