RelatedDB is a lightweight Swift wrapper around SQLite.

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RelatedDB is a lightweight Swift wrapper around SQLite.


  • iOS 13.0+
  • Xcode 12.0+
  • Swift 5.0+



CocoaPods is a dependency manager for Swift and Objective-C Cocoa projects.

To incorporate the RelatedDB library into your Xcode project utilizing CocoaPods, please reference it within your Podfile as shown below:

pod 'RelatedDB'

Swift Package Manager

Swift Package Manager is a tool for managing the distribution of Swift code.

Once you've configured your Package.swift manifest file, you may proceed to include RelatedDB in the dependencies section of the same file.

dependencies: [ .package(url: "", from: "1.1.5") ]


If you prefer not to use any of the dependency managers, you can integrate RelatedDB into your project manually. Just copy all the *.swift files from the RelatedDB/Sources folder into your Xcode project.


Connect to a Database

import RelatedDB

let db = RDatabase()

You can also specify the database filename or the complete path. The default filename database.sqlite, and the default path is Library/Application Support.

let db = RDatabase(file: "db.sqlite")
let db = RDatabase(path: "yourpath/db.sqlite")

Define Object

RelatedDB provides a protocol that helps to manipulate database rows as regular objects.

class User: NSObject, RDObject {

  @objc var userId = 0
  @objc var name = ""
  @objc var age = 0
  @objc var approved = false

  class func primaryKey() -> String {
    return "userId"

By creating the User class above, RelatedDB will automatically create the following SQLite Table for you:


Note: Since all the RDObject class property names will be used in SQLite commands, try to avoid using SQLite keywords in your class definition.

Insert Object

Using the User class above, creating an object would look like this:

let user = User()

user.userId = 1001 = "John Smith"
user.age = 42
user.approved = false


Update Object

An existing object can be updated:

user.age = 43


Insert vs. Update

If you are not 100% sure if an object already exists in the database or not, then you can use the following methods as well:


It will try to execute the INSERT command first and if it fails (silently), then executes the UPDATE command.

Also, you can use


which will try to execute the UPDATE command first and if it fails (silently), then executes the INSERT command.

Delete Object

An existing object can be deleted:


Fetch Object(s)

Fetching one object would look like:

let user = User.fetchOne(db, key: 1001)

Fetching multiple objects can be done in the following ways:

let users = User.fetchAll(db)

let users = User.fetchAll(db, "age > 40")

let users = User.fetchAll(db, "age = ?", [42])

let users = User.fetchAll(db, "age >= :min AND age <= :max", [":min": 18, ":max": 99])

You can also use the limit and offset parameters.

let users = User.fetchAll(db, limit: 10)

let users = User.fetchAll(db, "age > 40", limit: 5, offset: 10)

Serial Execution, Thread Safety

The database write actions are serialized. This means, the Insert, Update and Delete actions will be executed one after the other (managed by RelatedDB) automatically.

The Fetch methods are thread-safe. This means you will have back the results in the same thread you have initiated the request from.

Note: You can initiate both read and write actions from any thread you like.

Data Types

RelatedDB can manage the following data types: Bool, Int8, Int16, Int32, Int64, Int, Float, Double, String, Date, Data.

Date Format

The Date values will be stored in the database as ISO formatted String. The default format is ISO 8601 ("1970-01-01T01:01:01.000Z"), produced by the ISO8601DateFormatter class.

You can also specify your own date format by using:

let formatter = DateFormatter()
formatter.locale = Locale(identifier: "en_US_POSIX")
formatter.timeZone = TimeZone(secondsFromGMT: 0)
formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"


Note: You only need to specify the date format once in your codebase. Practically before doing any database action.

Values Dictionary

Although managing the database rows as objects is an easy and elegant way, you might want to manage the data as Dictionary instead.

Insert (using Dictionary)

Insert a new object as Disctionary:

let values: [String: Any] = ["userId": 1001, "name": "John Smith", "age": 42, "approved": false]

db.insert("User", values)

Update (using Dictionary)

Update an existing object as Dictionary:

let values: [String: Any] = ["userId": 1001, "age": 43]

db.update("User", values)

The primary key must be included in the values Dictionary. Otherwise, nothing will happen.

Fetch Result(s) (as Dictionary)

Fetching one object as Dictionary:

let user = db.fetchOne("User", key: 1001)

In this case, the result type will be a [String: Any].

Fetching multiple objects as Dictionary:

let users = db.fetchAll("User")

let users = db.fetchAll("User", "age > 40")

let users = db.fetchAll("User", "age = ?", [42])

let users = db.fetchAll("User", "age >= :min AND age <= :max", [":min": 18, ":max": 99])

In the cases above, the result types will be a [[String: Any]].

Convert Object (to Dictionary)

Convert an existing object to Dictionary:

let values = user.values()

Date Values (in Dictionary)

When using a values dictionary (to insert or update data), the Date values can be placed into the Dictionary as both Date or ISO formatted String.

When fetching data (as dictionary), the Date values will always be represented in the Dictionary as ISO formatted String.

Batch Update

You can update multiple objects by specifying a condition.

let values = ["approved": true]

User.updateAll(db, values, "age >= ? AND age <= ?", [30, 35])

Alternatively, update one object by specifying the primary key value.

let values = ["approved": true]

User.updateOne(db, values, key: 1001)

Batch Delete

You can delete multiple objects by specifying a condition.

User.deleteAll(db, "age >= ? AND age <= ?", [30, 35])

Alternatively delete one object by specifying the primary key value.

User.deleteOne(db, key: 1001)

Count Objects

You can get the number of objects by specifying a condition.

let count = User.count(db)

let count = User.count(db, "age > 40")

let count = User.count(db, "age >= ? AND age <= ?", [30, 35])

Check Objects

You can check whether an object exists or not (by specifying the primary key value).

if (User.check(db, key: 1001)) {
  // do something	

Or you check whether a set of objects exist or not (by specifying a condition).

if (User.check(db, "age >= ? AND age <= ?", [30, 35])) {
  // do something	

Create Observer

For refreshing the user interface upon database changes, you can use the Database Observers.

Checking all the possible changes for the User class would be:

let types: [RDObserverType] = [.insert, .update, .delete]

let observerId = User.createObserver(db, types) { method, objectId in
  // do something

However you can narrow down the number of changes by using a condition:

let observerId = User.createObserver(db, types, "OBJ.age > 40") { method, objectId in
  // do something

Also you can check only specific database changes (separated or combined) by using the following Observer types: .insert, .update, .delete.

To get notified about new users, but not the updated and/or deletes ones:

let observerId = User.createObserver(db, .insert) { method, objectId in
  // do something

Or to get notified about deleted users dedicated would look like this:

let observerId = User.createObserver(db, .delete) { method, objectId in
  // do something

Remove Observer

Once a Database Observer no longer required, you can remove it by using:

User.removeObserver(db, observerId)

Execute Plain SQL

If you would ever need it, you can execute plain SQL commands.

db.execute("DELETE FROM User WHERE age = 42;")

Drop Table, Create Table

Although the SQLite tables are created automatically, you can also DROP and/or CREATE tables manually.



In these cases, the User class also needs to be defined first.

Cleanup Database

If you would ever need, all the tables can be destroyed and recreated by using:


Error Handling

The crucial issues will cause a fatalError, every other situation will be reported in the Xcode output window.

You can alter the debug level by using:





The RelatedDB toolkit is in its initial release. It is functional and can handle most workloads. However, there are some features that are currently not supported:

  • Database migration
  • Database encryption
  • Combine framework integration

© Related Code 2022 - All Rights Reserved


  • Swift Tools 5.1.0
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Last updated: Tue Jan 16 2024 04:07:21 GMT-1000 (Hawaii-Aleutian Standard Time)