NSPredicate problem with column name
The Predicate Programming Guide from Apple says:
%@ is a var arg substitution for anobject value—often a string, number,or date.
%K is a var arg substitutionfor a key path.
When string variablesare substituted into a format stringusing %@ , they are surrounded byquotation marks. If you want tospecify a dynamic property name, use%K in the format string.
So, in your case, you need to put %K as a keypath to columnName, not %@ which will be added with quotation marks:
NSPredicate *refQuery = [NSPredicate predicateWithFormat: @"%K == %@", columnName, value];Hope this clear your doubts.
Very weird, but I think I have solved it by doing the following:
NSNumber *value = [NSNumber numberWithInteger: 2];NSString *columnName = @"something_id";NSString *predicate = [NSString stringWithFormat: @"%@ == %@", columnName, value];NSPredicate *refQuery = [NSPredicate predicateWithFormat: predicate];