PyQt5：为什么我不能更改可编辑标签的值？

Question

这是一个有可编辑标签的程序。我想在更改标签时打印标签的值。当我在主窗口上编辑标签的值时，标签的文本值不会更改。

from PyQt5 import QtCore, QtGui, QtWidgets


class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(200, 200)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(50, 50, 100, 50))
        font = QtGui.QFont()
        font.setPointSize(20)
        self.label.setFont(font)
        self.label.setAlignment(QtCore.Qt.AlignCenter)
        self.label.setTextInteractionFlags(QtCore.Qt.LinksAccessibleByMouse|QtCore.Qt.TextEditable|QtCore.Qt.TextEditorInteraction|QtCore.Qt.TextSelectableByKeyboard|QtCore.Qt.TextSelectableByMouse)
        self.label.setObjectName("label")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(60, 120, 75, 23))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)

        print(x)


        self.pushButton.clicked.connect(self.saveChanges)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.label.setText(_translate("MainWindow", "Hello"))
        self.pushButton.setText(_translate("MainWindow", "Save"))

    def saveChanges(self):
        print(self.label.text())

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

在此代码中，我更改标签上的文本并按保存后，self.label.text()仍返回'Hello'。为什么？有办法解决这个问题吗？