pause method
暂停消息流监听 Pause message flow listening
Implementation
bool pause() {
assert(_channel != null, 'You must call setMethodChannel() first');
if (!_supportPlatform || _channel == null) return false;
if (_streamSubscription != null && !_streamSubscription!.isPaused) {
_streamSubscription!.pause();
return true;
}
return false;
}