python - 如何加载 Qt Designer UI 文件

Question

import sys
from PyQt5.uic import loadUi
from PyQt5 import QtWidgets
from PyQt5.QtWidgets import QDialog, QApplication, QWidget
from PyQt5.QtGui import QPixmap
from PyQt5 import uic


class WelcomeScreen(QDialog):
    def __init__(self):
        super(WelcomeScreen, self).__init__()
        uic.loadUi("welcomescreen.ui",self)

app = QApplication(sys.argv)
welcome = WelcomeScreen()
widget = QtWidgets.QStackedWidget()
widget.addWidget(welcome)
widget.setFixedHeight(800)
widget.setFixedWidth(1200)
widget.show()
try:
    sys.exit(app.exec_())
except:
    print("Exiting")

[Errno 2] 没有这样的文件或目录：'welcomescreen.ui'

谁能解释一下？我对 PyQt5 还很陌生，并且陷入了这个问题。您的帮助将不胜感激。