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I have this app built with React Native v0.44. The current version is 0.48 but I haven't had time to upgrade during the summer, and when I tried to do so I got all kinds of weird dependency errors so I decided to stick with 0.44 for a little while longer. Yesterday I bought myself a new Macbook to finally put my old choking Macbook Air from 2012 out of its misery. I cloned my git repo, ran npm install, but when I tried to launch the app in the iOS simulator it stopped with the following error: Unable to resolve module ReactComponentTreeHook from node_modules/react-native/Libraries/Performance/Systrace.js I tried to clean up and reinstall a couple of times since that usually solves quite of lot of dependency errors, but this error persisted and I had no clue what was causing it. After searching the Internet for a little while I found this page presenting a couple of possible solutions worth trying . The first solution suggests using react-native-git-upgrade, and that's t...

Developing a React Native app for both iOS and Android at the same time comes with some challenges. One of them is how to best organize your source code in a version control system such as Git. Even though most of the code will run on both platforms, there will also be quite a lot of things that need to be addressed differently for each platform. A good approach for handling these differences is to implement a suitable Git branching strategy. Being a solo developer I have the luxury to decide exactly how I want it to fit my needs, so I started out by writing down the following "requirements": I want to have all my code in a single Git repository I need separate branches for the iOS and Android versions I want to be able to develop all features shared by iOS and Android in a single branch to make everyday development as smooth as possible I want merging to be painless I want to avoid cherry-picking commits between branches I want separate branches for development and...

In the React Native documentation it's possible to read about how to create a signed APK for release . But what if you only want to create an unsigned debug APK that doesn't require a developement server to run on device? Couldn't find anything in the official docs about this, but as usual Stack Overflow provided some great information, through  this thread with the following simple and efficient solution: First, from your app's root dir, run the following command: react-native bundle --dev false --platform android --entry-file index.android.js --bundle-output ./android/app/build/intermediates/assets/debug/index.android.bundle --assets-dest ./android/app/build/intermediates/res/merged/debug When I ran it the first time I got some strange error, something about not being able to open a .babel.json file. Ran the command again, and no problem the second time. Then the second and final step: cd android ./gradlew assembleDebug After this you should be able...

Reloading a React Native app in the Android emulator is as easy as just double tapping the R key on the keyboard. But to do reload on device you need to bring up the developer menu to find the 'Reload' option. Shouldn't be that hard, right? You're just supposed to shake the device, or press the hardware menu button on older devices. Well, my old ASUS device doesn't react to any shakes, and neither does it have a hardware menu button. So how do I open the menu? Couldn't find any information in the current React Native docs about it, but finally found a solution in this documentation for React Native v0.27 ! Don't know if things have changed between v0.27 and v0.43 to render the information obsolete, but at least it did the trick for me. Just type the following command from a command line: adb shell input keyevent 82 It's also possible to exchange 82 for KEYCODE_MENU if you feel like typing a few more characters. :-) adb shell input keyevent KEYCOD...

A couple of days back I got this weird error in the Android version of my React Native app that never happens on iOS. The error seemed to be completely random and appeared every once in a while when I tapped an item in a list to view its details. Every time it happened, the app crashed with the following cryptic error message: undefined is not an object (evaluating '_props[registrationName]') Nothing in the stacktrace that caught my eye, and an error that seemingly had no direct connection to my own code. Scanned the Internet and especially Stack Overflow for clues but couldn't find anything related. Today, a few days after the bug first appeared, I decided to try to hammer it out once again. Launched the Android emulator and sure, the bug was still there and just like before it seemed to happen randomly. Ran a desperate Google search for the error message, and this time it resulted in this interesting hit at the top:  http://stackoverflow.com/questions/43674781/und...

I'm working on the Android version of a React Native (v0.43.4) app on my Windows 10 machine, which has turned out to be a real pain compared to working on the iOS version on my Mac. I've got everything set up with Android Studio, platform tools, the Android emulator and so on. Running my app in the emulator also works, but almost every single time I issue the react-native run-android command, it fails with the following error from the React Packager: EPERM: operation not permitted, lstat <some_path_here> I have no idea what this problem is or why it happens. I don't even have to make any changes to the code or included libraries for it to appear. It's enough to just stop the React Packager and run react-native run-android again to get the error. It's really starting to get on my nerves since rebuilding seems to be required a lot more often on Windows than what I'm used to on OS X. I'd love to know what causes this, but until I manage to figure...

React Native together with Redux is a great combination of technologies for building a cross-platform mobile application. If you haven't worked with React, Redux (or similar frameworks) there will definitely be a steep learning curve to understand the key concepts and how everything works. But once you get the hang of it, you'll find yourself creating new components in no time, with code that feels very stable and maintainable. The fact that React Native and Redux are completely independent of each other gives you a lot of flexibility when it comes to how to use them in your app. This is of course mostly a very good thing, but it can also be a bit confusing at times. One of the things that took me quite some time to figure out was how to best construct my components, when I should use Redux container components, what should be injected from the container components to the presentational components and so on. If you don't decide how to solve things like these early on in...

I'm not sure about the best/correct way to rename an app created in React Native for iOS. Some solutions that I found require you to change some of your code, update package.json, run react-native upgrade , and clean up files that use the old name. That sure sounds like the correct way of doing it. But it also sounds like a lot of work, if all you want to accomplish is to change the text that appears under the app icon when installed on device. What I'm doing instead is to just open the app's Xcode project, click on the root node of the project structure, then the Info tab, and finally just update the value of "Bundle name" from ${PRODUCT_NAME} to whatever hard coded app name you want displayed. As long as that doesn't cause any other problems, I'll just stick to that solution. KISS.

So, who am I and what is this blog about? My name is Markus Ranner, a Swedish software developer with 15+ years of experience, mostly with backend focus using Java but also numerous other programming languages. In 2012 I started looking into mobile development out of curiousity, and began building an iOS app in Objective-C just to learn the language, as well as the iOS platform and the whole Apple eco system. After only about three months of development I released my first version of Avocado Meal Planner on the App Store. And from there on I knew that I wanted to do more mobile development! Avocado Meal Planner for iOS I didn't realize it back then because I had nothing to relate to, but it was actually quite a success right from the start with several hundreds of downloads each day! Unfortunately the first version wasn't all that good, so not many people wanted to pay for the full version. But just knowing that people all around the world were downloading and using ...