感谢作者，这本书非常棒，对我的帮助很大。

As a beginner in Flutter, it is very lucky to find a suitable introductory book. The author understands the thoughts of front-line developers when they are learning, and can throw out a simple example and explain each line of code in detail, while integrating common knowledge points into the example. It is a great guiding strategy! Now I see the section of a complete Flutter application, and I have some confusion as a beginner; in the section on global variables and shared states, I type the code step by step, and classes like Profile and NetCache will cause errors. I hope that the tutorial can also write out the custom classes involved and the dependencies involved step by step. This will allow users to step away from the source code when they are typing the code, and the source code will only serve as a final reference for debugging.