What is App OnStart
The App OnStart property allows you to run formula for your app when it is loaded. Whether you are running your Power App on a mobile, embedded in Microsoft Teams, or one of the other many ways to launch an app, this property will run before anything else in your app. This makes it a good starting point for initializing information such as variables, collections, data and app settings.
How to use App OnStart
The OnStart property can be found by selecting your App from the Tree View, then navigating to the drop-down properties in the top left – then finding OnStart.
In this example I use it to set the color values for my application which are stored in a variable and used throughout multiple elements in my screen. Setting the value here allows me to ensure my app will always load the correct color scheme, every time the app loads.
Using App OnStart in the Power Apps Studio
Its worth mentioning that the OnStart property will not run in the Power Apps Studio as the app would have already loaded before you make or amend changes to the property. If you want to see the effects of your formula in the Power Apps Studio, you need to select the ellipsis next to the App in the Tree View and select Run OnStart.