如何检查pyqt中是否选中了复选框

我正在尝试根据是否选中复选框来创建条件语句.我尝试了类似下面的内容,但它总是返回true.

self.folderactive = QtGui.QCheckBox(self.folders)
self.folderactive.setGeometry(QtCore.QRect(50, 390, 71, 21))
self.folderactive.setObjectName(_fromUtf8("folderactive"))
if self.folderactive.isChecked:
    folders.createDir('Desktop')
    print "pass"
elif not self.folderactive.isChecked:
    folders.deleteDir('Desktop')
    print "nopass"

有没有办法获得是否选中复选框的bool值？