Changing the label progresivelly (Custom tkinter)

Question

I've been trying to program some kind of countdown in python with UI. It's my first time working with Custom tkinter. I've encountered a small problem where if I input the time, the label won't change as it should. If you know how to change the text of the label into 00:00 format and make it change progresivelly, please let me know.

I've tried many things I can't name, if anyone's interested in the whole code, here:

from customtkinter import *
from PIL import Image
import time

app = CTk()
app.title('Countdown, hopefully')
app.geometry("500x400")
set_appearance_mode('light') #or 'light'


minutes, seconds = 0, 0
switch_var_1 = StringVar(value="off")


def countdown(t):

    def therest():
        setted_text.configure('{minutes:02d}:{seconds:02d}')

    while t:
        mins, secs = divmod(t, 60)
        timer = '{:02d}:{:02d}'.format(mins, secs)
        therest()
        print(timer, end = "\r")
        time.sleep(1)
        t -= 1

    print("ring")

def switch_event():
    if switch_var_1.get() == 'on':
        set_appearance_mode('dark')
    elif switch_var_1.get() == 'off':
        set_appearance_mode('light')

def start():
    t = time_entry.get()
    countdown(int(t))


entry_frame = CTkFrame(
    master=app,
    width=234,
    height=55,
    corner_radius=7,
    bg_color='transparent',
    fg_color='transparent'
)

time_entry = CTkEntry(
    master=entry_frame,
    placeholder_text='Enter the time (in seconds):',
    placeholder_text_color=('gray', '#e3d296'),
    text_color=('black', '#ffe894'),
    border_color=('gray', '#e3d296'),
    border_width=3,
    width=200,
    height=25,
    corner_radius=7
)

setted_text = CTkLabel(
    master=entry_frame,
    text='00:00',
    font=('Brass Mono', 20),
    text_color=('black', '#ffe894')
)

def set_text():
    setted_text.configure(text=f"{time_entry.get()}")

button_entry = CTkButton(
    master=entry_frame,
    text='Set',
    bg_color='transparent',
    fg_color='transparent',
    text_color=('black','#ffe894'),
    border_color=('gray', '#e3d296'),
    hover_color=('#d9d9d9', 'black'),
    corner_radius=1,
    height=25,
    width=40,
    border_width=3,
    command=set_text
)

switch_1 = CTkSwitch(
    master=app,
    text='Mode',
    text_color=('black', '#ffe894'),
    command=switch_event,
    variable=switch_var_1, onvalue="on", offvalue="off",
    progress_color='#ddc774',
    button_color=('black', '#ffe894'),
    button_hover_color=('#3c3c3c', '#ffeeac')
)

button_start = CTkButton(
    master=entry_frame,
    text='Start Countdown',
    bg_color='transparent',
    fg_color='transparent',
    text_color=('black','#ffe894'),
    border_color=('gray', '#e3d296'),
    hover_color=('#d9d9d9', 'black'),
    corner_radius=7,
    height=25,
    width=40,
    border_width=3,
    command=start
)


switch_1.place(relx=1, rely=0.9, anchor='se')
time_entry.place(relx=0, rely=0, anchor='nw')
button_entry.place(relx=1, rely=0, anchor='ne')
entry_frame.place(relx=0.1, rely=0.1, anchor='nw')
setted_text.place(relx=0, rely=1, anchor='sw')
button_start.place(relx=1, rely=1, anchor='se')

app.mainloop()

Answer 1

Edit: Adding screenshot.

I've encountered a small problem where if I input the time, the label won't change as it should.

Add app.update() and setted_text.configure in countdown(t) function.

Snippet:

def countdown(t):

    def therest():
        setted_text.configure('{seconds:02d}')

    while t:
        mins, secs = divmod(t, 60)
        timer = '{:01d}'.format(secs)
        
        therest()
        print(timer)
        setted_text.configure(text=timer)  
        time.sleep(1)
         
        t -= 1
        app.update() 
        
    print("ring")
    setted_text.configure(text='ring')

Screenshot: