In the Code view, you can view and modify the code in a UI file (.ui.qml) or component file (.qml) that is generated when you create components in the 2D or 3D view and specify their properties in Properties.
You can also view and modify other types of text files.
To open the search dialog in the Code view, go to Edit > Find/Replace > Find/Replace. You can also select Ctrl + F.
You can use a subset of the functions available in the Edit mode:
Available under certain Qt licenses.
Find out more.