指定した順で配列の値を並べる

sort_ids.swift

var mtCategoryIds = [1,2,3,4,5,7,8,9]
var savedCategoriesOrder = [3,7,2,1,5,4,6]
var dispCategoryIds: [Int] = []

for categoryId in savedCategoriesOrder {
    if let index = mtCategoryIds.indexOf(categoryId) {
        dispCategoryIds.append(categoryId)
        mtCategoryIds.removeAtIndex(index)
    } else {
        if let index = savedCategoriesOrder.indexOf(categoryId) {
            savedCategoriesOrder.removeAtIndex(index)
        }
    }
}

dispCategoryIds = dispCategoryIds + mtCategoryIds