if-let in ObjC

iflet.m

#import <Foundation/Foundation.h>
 
#define iflet(LHS, RHS) \
	for (id obj_ = (RHS); obj_ != nil;) \
		for (LHS = (obj_ ?: (RHS)); obj_ != nil; obj_ = nil)
 
int main(int argc, char *argv[]) {
	@autoreleasepool {
		NSString *x = nil;
		NSString *y = @"y";
		
		iflet(NSString *z, x) {
			NSLog(@"x is non-nil: %@", z);
		}
		
		iflet(NSString *z, y) {
			NSLog(@"y is non-nil: %@", z);
		}
	}
}
 
/* outputs:

Untitled[44105:2794964] y is non-nil: y

*/

thanks to Justin for improving this macro: https://twitter.com/jspahrsummers/status/570995129919500288 / https://twitter.com/jspahrsummers/status/570996870421458944

Do you have a way to add an else case? This is what I came up with and it seems to work but I'm not sure if I overlooked anything.

#define iflet(LHS, RHS) \
    for (BOOL b_ = YES; b_ != NO;) \
        for (id obj_ = (RHS); b_ != NO;) \
            for (LHS = (obj_ ?: (RHS)); b_ != NO; b_ = NO) \
                if (obj_ != nil)