How to override a string in string localized file for a target

Question

I have a general localized file for all targets in my application. for a specific target I want to override an string value

general localized string file:

"string1" = "1"
"string2"= "2"
"string3" = "3"
"string4"= "4"

I want to set "string4" to "four" just for one of targets.

NSLocalizedString(@"string4", nil)

---> for all targets except one: "4"
---> for that specific target: "four"

I don't want to write a condition and say read from general localize for all targets but for that specific target read from somewhere else.

According to this answer https://stackoverflow.com/a/23066894/4468859

NSLocalizedStringWithDefaultValue(@"string4", @"OverrideLocalizable", [NSBundle mainBundle], NSLocalizedString(@"string4", nil), nil);

Is this way has performance problem or other problems or is it ok?