Python PyQT5-添加下拉框，现在应用程序崩溃

我添加了一个下拉框，因此单击按钮后，它将提示输入IP地址，并在下拉框中为您提供一些选项

添加下拉框后，应用程序崩溃。我试图将他们选择的选项存储到一个变量中

一旦选择该选项并检查IP地址，它将从那里执行一些操作

import sys
import re

from PyQt5.QtCore import QRect
from PyQt5.QtWidgets import (QApplication, QWidget, QInputDialog, QLineEdit,
                             QLabel, QVBoxLayout, QPushButton, QComboBox)
from PyQt5.QtGui     import QIcon

class App(QWidget):

    def __init__(self):
        super().__init__()
        self.title  = 'IP / Domain'
        self.left   = 50
        self.top    = 50
        self.width  = 640
        self.height = 480

        self.initUI()

    def initUI(self):
        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        self.label = QLabel()
        self.label.setStyleSheet("color: green; font: 16px;")

        layout = QVBoxLayout()
        layout.addWidget(self.label)
        layout.addWidget(QPushButton("Enter IP-address", clicked=self.getText))
        self.setLayout(layout)        



        self.show()   

    def getText(self):


        userInput, okPressed = QInputDialog.getText(
                self,
                "Input IP-address", 
                "Your IP-address:", 
                QLineEdit.Normal, "")

        centralWidget = QWidget(self)
        userselection,self.setCentralWidget(centralWidget)
        userselection,self.comboBox = QComboBox(centralWidget)
        userselection,self.comboBox.setGeometry(QRect(40, 40, 491, 31))
        userselection,self.comboBox.setObjectName(("ip"))
        userselection,self.comboBox.addItem("domain")

        if okPressed:                       # and userInput != '':
            #print(userInput)
            if userInput.strip():
                self.ipFormatChk(userInput)

在此处为IP地址运行代码

            else:
                self.label.setStyleSheet("color: red; font: 24px;")
                self.label.setText("Input line is empty, enter IP-address")
        else:
            self.label.setText("")

    def ipFormatChk(self, userInput): 

        pattern = r"\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\." \
                  r"(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b"

        if re.match(pattern, userInput) and userselection is 'ip':
            additionalText = "This is IP-address"
            self.label.setStyleSheet("color: lightgreen; font: 24px;")

        if re.match(pattern, userInput) and userselection is 'ip':

在这里执行操作

        else:
            additionalText = "This is NOT an IP-address"
            self.label.setStyleSheet("color: red; font: 24px;")

        self.label.setText("{} <- {}".format(userInput, additionalText))

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex  = App()
    sys.exit(app.exec_())

其他：
additionalText=“这不是IP地址”
self.label.setStyleSheet（“颜色：红色；字体：24px；”）
self.label.setText（“{}为什么不在控制台中运行代码并读取回溯？找到了一个解决方法。将其更改为在输入IP地址后弹出下拉框。