There are 2 ways to load .kv file into code or application

1. By name

   When we write the code, we will make the App class. For this method, the file name and application class are the same, and save the kv file with appclassname.kv . 
   Kivy looks for a Kv file with the same name as your App class in lowercase, except for "App" if it ends in "App", for example:

    classnameApp --- & gt; classname.kv 

   If this file defines a root widget, it will be attached to the root attribute of the application and used as the base of the application widget tree.

   Sample code on how to use the .kv file in kivy, below:

   # code how to use the .kv file in kiw   # import cool module import kivy   # The base class of your application inherits from the class application. # app: always refers to your application instance from kivy.app import App < p>   # this limits the kivy version ie # below this version you cannot # use the application or software # optional write this kivy.require ( '1.9.1' )   # define the application class # and just skip the rest write on the cfile # no need to go # can also define a function in it class kvfileApp (App): pass   kv = kvfileApp () kv.run ()

   Save the .kv file code under the same name as the application class —

   Label: text:   ( '[b] Hello [/ b] [color = ff0099] World [/ color]' '[color = ff0099] Hello [/ color] [b] World [/ b]' '[b] Hello [/ b] [color = ff0099] World:):) [/ color]' ) markup: True font_size: '64pt'

   Exit:
   

2. Builder Method
   To use this method, you first need to import the Builder by writing

    from kivy.lang import builder 

   The developer can now directly load the entire file as a string or file. Doing this to load the .kv file as a file:

    Builder.load_file ('.kv / file / path') 

   or, to load, the kv file as a string:

   Builder.load_string(kv_string)

   # code to use the .kv file as a line in the main file # code how to use the .kv file in kiw   # import kivy module import kivy   # Your application base class inherits from the application class. # app: always refers to your application instance from kivy.app import App   # this is the import Builder from kivy.lang import Builder   # this limits the kivy version i.e. # below this version you cannot use the application or software # not be sure to write this kivy.require ( '1.9.1' )   # build the kv file as a string kvfile = Builder.load_string ( "" "  Tag: text: (& # 39; [b] Hello [/ b] [color = ff0099] World [/ color] // n & # 39; & # 39; [color = ff0099] Hello [/ color] [b] World [/ b ] // n & # 39; & # 39; [b] Hi [/ b ] [color = ff0099] World :) :) [/ color] & # 39;) markup: true   font_size: 64pt "" " )    # define the application class # and just skip the rest write on the cfile # not need to pass # can also define a function in it class kvfileApp (App): def build ( self ): return kvfile   kv = kvfileApp () kv.run ()

   Output: