Flutter is an open-source framework developed by Google to build iOS and Android apps from a single codebase. Launched in 2018, it has since received a great deal of attention and is now neck and neck with React Native as the top cross-platform development framework. When launched, Flutter focused primarily on mobile apps but is now able to build applications for web applications, Windows, MacOS, and Linux.
Flutter is based on the Dart programming language, a general-purpose open-source programming language also developed by Google. It was announced in 2011 and has since gained popularity for its use in building cross-platform mobile, web, and desktop applications. Dart is designed to be easy to learn and productive for developers, with a syntax that is similar to other C-style languages. Dart provides features like garbage collection, strong typing, async/await syntax for handling asynchronous operations, and an extensive set of libraries and tools.
Flutter employs a unique approach to UI rendering, where it controls the entire rendering pipeline, bypassing the native UI components of the underlying platform. This enables Flutter applications to have consistent behavior and appearance across different platforms, resulting in a native-like experience. It also allows for fast development and hot reloading, where changes to the code are instantly reflected in the app without requiring a full rebuild.
Flutter has gained popularity among developers for its ability to create high-performance applications with a single codebase, reducing the need for platform-specific development and maintenance.
Swift, on the other hand, is an open-source programming language, rather than an app development framework, and was created in 2014 as a modern, safe, and fast programming language for iOS, macOS, watchOS, and tvOS app development. Swift is designed to be easy to learn and use, with a syntax that is concise and expressive. It was intended to replace Objective-C as the primary programming language for Apple platforms. Swift combines the best features of various programming languages and introduces new concepts, making it efficient for writing robust and high-performance software. It has a strong focus on safety, with built-in features to prevent common programming errors and crashes.
Because it is not a development framework, comparing it to Flutter might not seem a particularly accurate comparison. However, as it is the primary programming language used for native iOS app development, it is important to know its strengths and weaknesses in comparison to cross-platform app development.
As mentioned, Flutter is a cross-platform app development framework, whereas Swift is a programming language, more aptly compared directly with Dart. However, as Dart is not often used outside of Flutter, and its success is largely tied to Flutter, they can almost (but not quite) be used interchangeably in the context of comparison. That said, any discussion of Flutter and Swift app development would be remiss in not mentioning the primary difference between the two:
Having covered the primary difference, let’s look into Flutter and Swift in greater depth.
If developing native iOS apps, learning Swift is essential, to say the least. Swift programming language has by and large succeeded Objective-C for iOS development, and is the best starting point for those wanting to build iOS apps. It is a modern, fast programming language, and designed to be easy to learn. Core strengths of the programming language include:
Flutter relies on the Dart programming language, a platform-neutral coding language that can on its own develop iOS and Android apps. It uses a Java-like syntax and is, like Swift, considered to be a great language for beginners to learn. Core strengths of the language include:
Essentially, Dart is possibly the best possible cross-platform coding language from a performance perspective but is still beaten (though not by much) in terms of performance and memory optimization by Swift for iOS-only application development. Swift is also much more lightweight as it does not require the addition of UI elements and a rendering engine built-in (though this is added by the Flutter framework, not Dart only).
There are a number of intangibles related to Dart and Swift coding languages that can inform the decision between the two languages. One is the prevalence and sustainability of the language – Swift is ubiquitous for iOS app development and at no risk of disappearing from the iOS mobile app development landscape. Dart, on the other hand, is heavily reliant on Flutter, and rarely used outside of it. If Flutter were to fall into disfavor, it is likely that Dart would soon be all but forgotten. This also informs other aspects of development, notably the availability of resources – there are more Swift developers available than Flutter developers available (6.1% for Swift compared to 3.7% for Flutter on GitHub).
The development process for a Swift app and a Flutter iOS app can be considered roughly the same. Swift is generally considered a very fast-paced coding language, allowing for speedy development and brevity of code. Flutter code (Dart) might be less speedy to write, but development time can be saved on the design and coding of the UI, through the use of widgets. These widgets can make simply designed apps generated by Flutter very quick to create, making Flutter a very good choice for MVP development. Features like hot reload also help to speed up delivery, allowing Flutter developers to test small changes on the fly. These features make any advantages gained by Swift’s less verbose and fast code generation largely moot if only considering iOS app development.
However, Flutter has far greater reach than Swift, as we’ve already established, allowing the same code to create apps across both iOS and Android, as well as web development, Linux, Windows, and macOS. Swift also allows for the reuse of code but is typically only used for iOS, iPadOS, MacOS, tvOS, and watchOS. If building cross-platform apps, there is no question that it is more efficient to use Flutter.
The median salary of Swift vs. Flutter developers is roughly the same, 83k$ in the US for Swift and 82k$ for Flutter. As we’ve established, if only considering iOS development, the difference in speed of development can be considered negligible, and is largely dependent on the skill of the development team and the nature of the project. Flutter is often seen as a top choice for MVP development, due to the built-in user interface elements called widgets, which allow a functional and intuitive design to be stood up in a very short time frame. The hot reload feature allows for rapid testing and display of small changes, which can help when trying to impress investors. For more complex and resource-intensive native applications (ie hardware, specific device components) Swift might be the faster development choice. Considering that salaries are roughly the same, and the difference in development time (other than for UI design and possibly MVP development) is not vastly different, either one will work for an iOS app development project.
If planning to build applications across multiple platforms, there is no question that Flutter is the way to go, unless specific performance metrics or highly specialized use of Apple hardware components (ie camera, GPS) is mandated for your application.
Cross-platform app frameworks always come with some degree of overhead. Flutter is no exception, but by most metrics, the difference is negligible. When tested by InVerita for CPU-intensive computations, Flutter performed better than Swift in some categories. For UI performance, Flutter and Swift were neck and neck for many tests, including framerate, with differences in how results were delivered. For instance, Flutter used less GPU% but slightly more CPU, and marginally more memory. Flutter only faltered in one test, for animations heavy enough to cause FPS drops. It was speculated that this might have had more to do with the Flare package used to render the vector animations. In other words, this might highlight a weakness in available packages rather than in Flutter itself.
Swift performed consistently and well in all categories, which is no surprise since it is a coding language built specifically to develop iOS apps. It was also the most lightweight option, delivering the smallest app size. Flutter iOS apps (and Android for that matter) are much larger, as they must contain the Flutter rendering engine, plus all the UI components. However, it is this larger app size that allows it to render UI as fast or nearly as fast as native iOS apps, because it requires no bridge to reach native iOS UI components.
Both Flutter and Swift have strong community support. The level of support for each is difficult to effectively gauge, as it depends on the metric you want to use. For instance, we can tell that Swift is the more established player and has been around longer simply by looking at the number of commits on GitHub – 150,947 for Swift, compared to 34,939 for Flutter, as of May 20, 2023. However, we also see a higher degree of community engagement in terms of the number of stars, with Flutter at 154k compared to 62.8k for Swift. According to last year’s StackOverflow survey (a 2023 survey is currently being conducted), Dart is slightly more popular than Swift among professional developers, at 6.67% compared to 5.18% for Swift. However, if you look at the number of questions asked on Stack Overflow, we can also see that there are more than double the questions (327,216) for Swift than there are for Flutter(161,992).
Regardless, we can see that both are very active and have strong community support. Both are seen to have strong documentation and are considered relatively easy to learn.
The quickest answer to this question is the most obvious as well – if you are only concerned with developing iOS apps (or watchOS, tvOS, MacOS, etc.) and want to deliver the best possible performance, a more lightweight application, or less resource-intensive, then Swift is the better choice. Flutter can deliver decent performance as well and can be better for certain MVP deployments, but for general-purpose native iOS app development, there is little reason to argue against using Swift.
If the question is when to use Swift (or native app development in general) over cross-platform app development, then there are only a few scenarios in which the additional cost makes sense. If there are very tight integrations with iOS app UI components that require frequent updates, native app development can be more efficient and scalable. If the app requires tight integration with Apple or Android device hardware components for very specialized functionality, then again, native app development might be the way to go. Without highly specific requirements tied to native coding or hardware, the cost of maintaining separate development teams across platforms is very hard to justify.
Flutter app development is almost always the best choice for any cross-platform development scenario, over native Swift and iOS development. Native and Flutter apps have similar performance profiles, making Flutter arguably the best cross-platform framework choice for native iOS development. It is an exceptional choice for MVP development, particularly if you want to leave open the possibility of later expanding to other platforms, including web and desktop. A Flutter demo app can be designed and delivered very quickly due to pre-built UI widgets.
The choice between Flutter vs. Swift is largely dependent on the requirements of your project. For native apps with high-performance requirements, you cannot beat a native coding language. Swift programming language has easily surpassed Objective-C as the top choice for a high-performance iOS project. A Flutter iOS app can deliver strong performance as well, but will be larger, and potentially chew up more system resources to deliver that performance. Flutter should be considered for MVP development scenarios, particularly if you are at all uncertain about restricting yourself to the Apple marketplace. It offers rapid UI design and can be configured to appear as a native iOS app using Cupertino widgets. For cross-platform development, Flutter is almost always a top choice.
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