buggy behavior with Chinese(Simplified)-Pinyin, 10 Key in QtQuick.TextInput on iOS

in ios 9.1. QML textinput have a bug, the Pinyin(for simplified Chinese) input method, input "tianmao", out is "timamaa". It should be "天猫" and other software work fine, IOS comes with the Pinyin input method, and can not be entirely deleted letters. If you enter any character in the textinput, and then enter the ‘tianmao’, , is able to get the word "天猫", is this bug?

qml的textinput有个bug，拼音输入法，输入tianmao，出来的是timamaa，没天猫字样，其他软件下是能出天猫字样的，ios自带的拼音输入法，而且不能完全删掉拼音。如果在textinput里输入了任何字符后，再打tianmao，是能显示天猫字样的，这是怎么回事呢？