ios - NSBundle mainBundle pathForResource: Not working unless @2x included -

i have files named: landing_load1@2x ...landing_load4@2x in project. (no non-retina files)

this code works:

for(int x=1; x < 5; x++){     nsstring * imagetitle = [nsstring stringwithformat:@"landing_load%i@2x", x];     uiimage * loadingimage = [uiimage imagewithcontentsoffile:[[nsbundle mainbundle] pathforresource:imagetitle oftype:@"png"]];      [loadingimages addobject:loadingimage]; } 

but doesn't work:

for(int x=1; x < 5; x++){     nsstring * imagetitle = [nsstring stringwithformat:@"landing_load%i", x];     uiimage * loadingimage = [uiimage imagewithcontentsoffile:[[nsbundle mainbundle] pathforresource:imagetitle oftype:nil]];      [loadingimages addobject:loadingimage]; } 

and doesn't work:

for(int x=1; x < 5; x++){       nsstring * imagetitle = [nsstring stringwithformat:@"landing_load%i", x];       uiimage * loadingimage = [uiimage imagewithcontentsoffile:[[nsbundle mainbundle] pathforresource:imagetitle oftype:nil]];       [loadingimages addobject:loadingimage]; } 

question: know don't have explicitly call @2x or specify file type, ideas why it's not working unless explicitly write whole file name out?

note: tested on ipad 4

record

nsstring * imagetitle = [nsstring stringwithformat:@"landing_load%i", x]; 

means have pair of graphics files resource - both "filename.png" , "filename@2x.png". or, alternatively, can used "alias" "filename.png" if have "filename@2x.png", have 2 possible variants: 1. use that

nsstring * imagetitle = [nsstring stringwithformat:"landing_load%i@2x", x]; 

or have both of files ("filename.png" , "filename@2x.png") resource.