ios crash due some fileds of regeocode is nil

[danieldai]

_formattedAddress __NSCFString * @"山西省晋城市沁水县靠近前土门上"
_country __NSCFString * @"中国"
_province __NSCFString * @"山西省"
_city __NSCFString * @"晋城市"
_district __NSCFString * @"沁水县"
_township id 0x0
_neighborhood id 0x0
_building id 0x0
_citycode NSTaggedPointerString * @"0356"
_adcode NSTaggedPointerString * @"140521"
_street id 0x0
_number id 0x0
_POIName __NSCFString * @"前土门上"
_AOIName id 0x0

[danieldai]

#40 can be fixed by this PR