“Write once and use everywhere” is the popular slogan associated with React Native technology, since it was introduced. React native allows the developer to build apps using only JavaScript. When you build Android and iOS apps with React Native, the same design can be used on both the platforms that is why it is made sure to create rich mobile UI and UX elements from declarative components. The main advantage of React Native is that you can reuse the code for writing apps on both Android and iOS versions. However, the aforementioned slogan is not entirely true! No doubt most of the codes can be reused between both the platforms, but in the end, no one can deny that both Android and iOS are two different operating platforms, and there exist so many differences. Below are mentioned the differences between the development of Android and iOS apps: THE OPERATING SYSTEM - With React Native, you can easily build applications for both systems - Android and iOS. However, if you’re working on a Windows system, it will become difficult for you to know whether the app will work on both systems or not. Windows is incapable to run XCode and its simulator, which is a macOS-only app. XCode is a very helpful tool while working on React Native applications. If you are working on Windows, Android Studio is the only reliable tool that helps you work on the Android version of the app. However, you can use macOS for both Android and iOS because Android Studio works perfectly fine on Apple’s Macbook. PLATFORM-SPECIFIC ELEMENTS - In the initial phase, it may seem obvious, but while using elements from the React Native library, you will face problems in the later stage. For instance, if you happen to choose Picker component, you will get different result in the Android emulator and iOS simulator. This is because JavaScript elements are compiled by React Native on to platform-specific elements for rendering. SHADOW STYLES - In Material Design, shadow style is different in iOS and Android. iOS apps feature simple icons and buttons without any shadow or floating elements whereas Android apps drop shadows in their buttons. When using React Native, you can use elevation property in order to have some kind of shadow in Android version. The elevation feature lifts any element above the standard elements to cast a shadow. This style of property leaves no shadow style on iOS apps. LINKING LIBRARIES - React Native is considered good when you have to develop mobile app from scratch. However, if there’s a need to add a single view or user flow to existing native applications, it is also very much possible with the help of third party library. The third party library is either added as a dependency or a react native link is created using the “library name”. Thereafter this link is given the run command. There are many libraries wherein manual linking has to be done. For performing manual library linking, you’ll be required to add codes in the Android and iOS files. Some knowledge of Java and Objective C may help you but you will get documentation with each library, which will make it easier for you to implement those libraries into the cross-platform app. There exist many differences when one has to build iOS apps with React Native or the Android apps. React Native is an awesome technology as it lets you reuse most of your code for both the systems. Most of the differences pop up in the layout of the application. At the same time, these limitations can also be an advantage because most of the problems will come up while developing Android apps using React Native. There are very less possibilities that you’ll face hiccups with iOS app development.