Conversion of IOS timestamps in R to UNIX epochs and readable dates

IosTimestampConvert.R

#Conversion to Unix Epoch
IosConvertEpoch  <- function(timestamp_vector){ 
  convUNIX <- timestamp_vector/1000000000+978307200
}


#Conversion to date
IosConvertDate <- function(timestamp_vector){ 
  convUNIX <- timestamp_vector/1000000000+978307200
  date <- as.Date(as.POSIXct(convUNIX ,tz = "", origin = "1970-01-01", 
                      tryFormats = c(
                                      "%Y-%m-%d %H:%M:%OS",
                                      "%Y/%m/%d %H:%M:%OS",
                                      "%Y-%m-%d %H:%M",
                                      "%Y/%m/%d %H:%M",
                                      "%Y-%m-%d",
                                      "%Y/%m/%d"), 
                                      optional = FALSE ))
              }


#For testing:
  #vector of IOS timestamps 
  # vec<-c(551000054000000000, 551004813978757632 ,551004862012363648, 551004894680455680)
  #function calls
  # IosConvertEpoch(vec)
  # IosConvertDate(vec)