Swift refactoring

add_or_append_to_dictionary.swift

// TL;DR: look at this cool thing in swift
let ibsTags = try ibsTagRecords().reduce(into: [Int64: [Int64]]()) {

  // this line here
  $0[$1.ibsID, default: []].append($1.tagID)
  
}

// V1 original

if $0[$1.ibsID] == nil {
  $0[$1.ibsID] = [$1.tagID]
} else {
  $0[$1.ibsID]?.append($1.tagID)
}

// V2 better than ruby's ||=

if $0[$1.ibsID]?.append($1.tagID) == nil {
  $0[$1.ibsID] = [$1.tagID]
}

// v3 the ultimate in readablity in only the way swift can
if $0[$1.ibsID]?.append($1.tagID) == nil { $0[$1.ibsID] = [$1.tagID] }

// v4 or the swift way
$0[$1.ibsID, default: []].append($1.tagID)

// This is the old way pre swift 4.1
$0[$1.ibsID] = ($0[$1.ibsID] ?? []) + $1.tagID