I have read in Arcgis docs to enable offline searching we need locator file. Can we get locator file without ArcGIS desktop/pro application. If yes, how do I get locator file?
Currently I am using IOS runtime sdk 100.0
Not at this time.
However, if you have an offline geodatabase (you can get that by taking a FeatureService offline, from ArcGIS Desktop's "Export for Runtime" tool, or from an MMPK), you could query against that. It's not as streamlined as using a Locator for geocoding (for example, the performance may not be optimized for geolocating, you might get more or fewer results than expected, you will not get a suggestions API, the geodatabase file could end up larger than the locator file would have), but depending on your requirements it could serve your purpose.
When you take the feature service offline, ensure that you include the field(s) you want to search on. Then once you have your AGSGeodatabaseFeatureTable, you can call queryFeaturesWithParameters:completion. Depending on the geometry type of the feature service you may need to process the results to get a suitable extent to zoom to.