To develop applications for Apple’s mobile operating system, iOS app development is primary. It involves coding and designing apps for iOS devices such as iPhones and iPads using programming languages such as Swift and Objective-C. A thorough understanding of Apple’s app development guidelines and practices is crucial to creating successful iOS apps.

Undoubtedly, the market for iOS apps has come a long way since its inception. Currently, the Apple App Store boasts a staggering 2.2 million iOS applications that users can access. In 2018 alone, the number of downloads surpassed 194 billion, indicating the colossal scale of this industry. Considering this massive market, it is evident that developing an iOS app with an efficient database for iOS can prove to be a profitable venture for businesses.

Understanding Databases

In mobile app development, it becomes imperative to make crucial decisions concerning the selection of tools and frameworks to achieve desired outcomes. However, equally significant is the role of databases in providing all necessary information to end-users, thereby enabling them to enjoy interactive experiences with the app. A database essentially comprises accessible data and typically manages data across most electronic devices.

For instance, the contacts on your phone serve as a database that allows you to store and modify contact information. In a similar vein, mobile apps heavily rely on databases, just as desktop apps do. Application databases are instrumental in running apps and governing user inputs.

The proper functioning of an app is a direct outcome of the data that it stores and filters. Such data transformations assume critical importance in ensuring the app performs optimally.

How to Select the Best Databases for iOS Apps?

Choosing the best database for iOS app development is dependent on your specific needs. If you need a lightweight and user-friendly database, then SQLite is an excellent choice. Conversely, if a more feature-rich database is necessary, then Realm may be a better option. 

SQLite is the most popular database for iOS apps due to its open-source nature, lightweight structure, and user-friendliness. Furthermore, it integrates seamlessly with Swift app development. Realm, which is also open-source and user-friendly. However, it is comparatively heavier than SQLite and does not offer as many features.

To help you make a more informed choice, here are the major factors that you should consider before you select a database for iOS application. 

Data Structure

How an app stores and retrieves data determines the data structure. The mobile apps manage data in various formats of data. For instance, online apps necessitate server access to function optimally, while offline apps save all data on the mobile device.

Synchronized apps function by saving data on mobile devices, while also working in offline mode. Whenever the device connects to the internet, the server automatically updates the data.

Data Volume

The quantity of data necessary to store and retrieve as essential application data is ‘data size’. The size of stored data varies based on the data format employed and the database’s capacity to distinguish data across multiple file systems and servers.

Hence, selecting the appropriate database for iOS entails considering the overall volume of data generated by the program at any given time.

Performance & Scalability

Certain databases cater to read-heavy applications, whereas others are better suited for write-heavy applications. For instance, MongoDB outperforms MySQL in handling vast amounts of unstructured data. In contrast, MySQL is faster in managing structured data.

A design that can scale efficiently commences with the selection of a database that can manage the Input/Output (I/O) demands of your app.

Data Security

When employing synchronized and decentralized storage, it is crucial to securely access, transfer, and store data. Authentication, data at rest, and data in motion all require careful consideration.

Authentication must be flexible, enabling standard, public, and customized authentication sources. Many apps necessitate anonymous access to function optimally. The database should grant granular control over data access and modification, enabling precise management of reading and writing access.

Top Databases for iOS App Development


SQLite is the most widely used relational database for iOS and Android platforms. This open-source, relational database is compatible with Swift and can work on multiple platforms, such as iOS and Android, due to its file-based system. However, objects must be converted to rows to be stored.

SQLite does not provide any cloud-hosted, cross-device, or synchronization capabilities. Only the application has managed security, with no user-based security. Additionally, it may experience performance issues when handling large applications, as it is not for them. Furthermore, SQLite is not scalable due to the limitations of relational databases.

As a result, it often requires a DAO or ORM (such as Core Data) to be used in conjunction with it.


Firebase offers a range of features that developers can customize to suit the specific requirements of an application, including a real-time database. This cloud-based key-value store enables data synchronization and can be accessed through an SDK, providing a straightforward and efficient way to create an MVP. As it is hosted on the cloud, Firebase offers scalability benefits and boasts a strong community of support for users. Furthermore, the platform offers an array of additional products beyond mobile databases, including authentication.

However, there are some drawbacks to using Firebase. Integrating the platform may increase the size of an application due to the addition of a third-party library. Additionally, the data model and query constraints of Firebase can impact performance and user experience. Cloud functions need to handle complex queries, which can create additional management burdens for developers. Furthermore, the platform does not support aggregation queries such as averages, sums, or counts. Scaling brings the need for sharding, which developers cannot manually configure in Firestore. Finally, conflict resolution in sync mode follows a “last write wins” protocol, which may lead to data loss in applications that allow multiple users.


Realm, previously known as MongoDB Realm, is an object-oriented open-source database management system. Unlike SQLite, which utilizes the SQL database language, Realm is based on C++, enabling developers to create object connections.

Realm is a strong contender as the optimal database for iOS application. It was specifically for mobile operating systems, including Android, iOS, Xamarin, and React Native. One of Realm’s advantages is its modernity, which allows it to outperform SQLite in terms of speed. Another important feature of Realm is its scalability, making it capable of handling numerous users and a substantial amount of data.

Developers can quickly access Realm’s well-written documentation, which aids in faster development processes. 

However, adding a third-party library increases the size of the app. Moreover, Realm’s community is smaller than those of SQLite and Firebase. Realm’s sync functionality presently only runs on AWS. However, support for Azure and GCP is coming soon.


Core Data, a framework supported by Apple, enables the saving of permanent and temporary app data, defining data types and relationships. Although not technically a database, it can use SQLite to store data. Core Data is a middleware that acts as an abstraction layer between an application and its data stored in the database.

Core Data is a professional data cleaning and conversion company that provides various services such as error removal from data files, accurate file format conversions, and table merging. Its close relationship with Apple provides an advantage when dealing with Apple-specific languages like Swift and Objective-C.

Core Data is the most extensive and fastest data storage solution available in the iOS ecosystem, and it prioritizes simplicity, reducing code writing by up to 70%. The framework supports binary, XML, and SQLite databases, allowing software engineers to focus on one language instead of multiple languages. Core Data also offers robust querying capabilities, input validation, and lazy loading of data, which enhances performance. Its graph component allows for effortless visualization of entities.

Despite its advantages, Core Data has some limitations. Because it’s just a framework, it inherits the disadvantages of the database it uses. It has a steep learning curve and additional overhead on top of using a database.


Keychain is an Application Programming Interface (API) to store sensitive data, including passwords and in-app purchase statuses. Since the data is encrypted, it’s an ideal option for storing critical information. Keychain is built into the security framework of iOS, eliminating the need for additional libraries.

Despite its advantages, Keychain has some limitations, including the fact that the framework is quite old and hasn’t been updated recently. Furthermore, its APIs haven’t been modernized, resulting in code that can be complicated when used with Swift.

Wrapping Up!

Trade-offs are often inherent in decision-making, especially when it comes to databases, which involve considerations of speed, size, and scalability.

Despite its reputation as a classic language for databases, SQLite can be slow, with the lowest write-throughput of any database. However, its widespread use makes it a popular choice for those familiar with databases.

In comparison, Realm offers advantages in terms of speed and scalability over both Core Data and SQLite, making it an attractive option for developers.

Core Data may not be as powerful as a full-fledged database, but it remains a useful tool for shortening development time and facilitating updates for feature enhancements. 

Therefore, when choosing a database for a mobile app, it’s crucial to consider the ability to adapt to changes over time.