Update progress bar from function outside the main class in Python Tkinter

I have initialized a progress bar and want to update it according to the function / thread which is outside the main class of Tkinter. I have tried all the solutions present over here similar to the problem but to no avail. Any help will be greatly appreciated. Here is my code:

from tkinter import ttk
import time
import tkinter as tk

def run():
    global progressBar
    progressBar['maximum'] = 100
    for i in range(0,100,25):
        time.sleep(0.05)
        progressBar["value"] = i
        progressBar.update()
        progressBar["value"] = 0
    progressBar["value"] = 100


class Main(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        buttonFrame = tk.Label(text="Progress Bar")
        buttonFrame.grid(column=0,row=0)

        progressBar = ttk.Progressbar(self, orient="horizontal", length=286,mode="determinate")
        progressBar.grid(column = 0, row = 3, pady=10)

        button1 = tk.Button(buttonFrame, text="Run Progress Bar" ,command = run)
        button1.grid(column = 0, row = 0)


app = Main()
app.mainloop() 

You have used OOP.You could make the most of the class.I have reconstitute your code(Also,there is an error in your code):

from tkinter import ttk
import time
import tkinter as tk

class Main(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.buttonFrame = tk.Label(text="Progress Bar")
        self.buttonFrame.grid(column=0,row=0)

        self.progressBar = ttk.Progressbar(self, orient="horizontal", length=286,mode="determinate")
        self.progressBar.grid(column = 0, row = 3, pady=10)

        # this shouldn't be run() or self.run().No "()" there(Or you can use lambda if you need to pass arguments).
        self.button1 = tk.Button(self.buttonFrame, text="Run Progress Bar" ,command = self.run) 
        self.button1.grid(column = 0, row = 0)

    def run(self):
        self.progressBar['maximum'] = 100
        for i in range(0, 100, 25):
            time.sleep(0.05)
            self.progressBar["value"] = i
            self.progressBar.update()
            self.progressBar["value"] = 0
        self.progressBar["value"] = 100


app = Main()
app.mainloop()