Question

I’m building a bunch of functions that will make my core data calls a bit nicer, and not so bloated.

Lets say I have a method that looks like this:

- (NSArray*)retrieveDataFrom:(NSString *) name where:(NSString *) where is:(NSString *) is {

   NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(%@ = '%@')", where, is];

   return [self retrieveDataFrom:name withPredicate:predicate];
}

and then sometimes I want to do something like this (for example):

[self retrieveDataFrom:@"table" where:@"id" is:int 2];

instead of this:

[self retrieveDataFrom:@"table" where:@"id" is:@"2"];

Is there a way to get a method to accept an argument without knowing its type?

Answer 1

Not directly. You can declare the input as NSObject * so it can take a NSString * or a NSNumber *, but you’re still stuck using NSNumber‘s ugly syntax.

[self retrieveDataFrom:@"table" where:@"id" is:[NSNumber numberWithInt:2]];

However, better syntax is coming soon in the form of Clang Language Extensions.

When these land, you’ll be able to write this instead:

[self retrieveDataFrom:@"table" where:@"id" is:@2];

At present, the LLVM website says these will be in llvm 4.0. The smart money says this will be in Xcode 4.4, but I doubt Apple is beholden to a statement on the LLVM website.