How do you pick a color for an app?
Consider the Content Legibility
Make sure that you don't put bright-colored app elements against a bright-colored background. Always maintain a contrast between the elements and the background of the app. When you need to choose the contrast ratio, you should start with a ratio of at least 4.5:1.
What Colour should my app be?
Due to such a multitude of reasons and emotions, blue is truly the best color for mobile app design.