ios - Core Data Swift - Not Creating SQLite file -

i new core data , have followed few tutorials. don't seem able access .sqlite file either on simulator or on iphone 6. debugger prints following. can provide assistance please?

2015-07-17 11:31:28.006 rockford[390:32594] coredata: error: (1) i/o error database @ /var/mobile/containers/data/application/d2a80335-e681-4194-944d-cae66f80efa6/documents/rockford.sqlite. sqlite error code:1, 'unknown database zrockford'
2015-07-17 11:31:28.011 rockford[390:32594] coredata: error: -addpersistentstorewithtype:sqlite configuration:(null) url:file:///var/mobile/containers/data/application/d2a80335-e681-4194-944d-cae66f80efa6/documents/rockford.sqlite options:{ nsinfermappingmodelautomaticallyoption = 1; nsmigratepersistentstoresautomaticallyoption = 1; } ... returned error error domain=nscocoaerrordomain code=256 "the operation couldn’t completed. (cocoa error 256.)" userinfo=0x170460a40 {nssqliteerrordomain=1, nsunderlyingexception=i/o error database @ /var/mobile/containers/data/application/d2a80335-e681-4194-944d-cae66f80efa6/documents/rockford.sqlite. sqlite error code:1, 'unknown database zrockford'} userinfo dictionary { nssqliteerrordomain = 1; nsunderlyingexception = "i/o error database @ /var/mobile/containers/data/application/d2a80335-e681-4194-944d-cae66f80efa6/documents/rockford.sqlite. sqlite error code:1, 'unknown database zrockford'";

just delete app simulator/device , run again. may happen when make changes in core data part of project , device have created database.