ios app crashed when hiding keyboard

import QtQuick 2.3
import QtQuick.Controls 1.2

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    Rectangle{
        anchors.fill: parent
        focus: true
        TextField {
            text: qsTr("Hello World")
            anchors.centerIn: parent
        }
    }
}