if-let and guard macros for Objective C

iflet.m

#import <Foundation/Foundation.h>

// VARIABLE must be a variable declaration (NSString *foo)
// VALUE is what you are checking is not nil
// WHERE is an additional BOOL condition

#define iflet(VARIABLE, VALUE) \
    ifletwhere(VARIABLE, VALUE, YES)

#define ifletwhere(VARIABLE, VALUE, WHERE) \
    for (BOOL b_ = YES; b_ != NO;) \
        for (id obj_ = (VALUE); b_ != NO;) \
            for (VARIABLE = (obj_ ?: (VALUE)); b_ != NO; b_ = NO) \
                if (obj_ != nil && (WHERE))



// Called just like the swift verstion
// guard(1 < 2) else {
//     return
// }

#define guard(CONDITION) \
    if (CONDITION) {}

#define guardletwhere(VARIABLE, VALUE, WHERE) \
    ifletwhere(VARIABLE, VALUE, WHERE) {}



int main(int argc, char *argv[]) {
    @autoreleasepool {
        NSString *x = @"asdf";
        NSString *y = nil;
        
        iflet(NSString *z, x) {
            NSLog(@"x is not nil");
        }
        
        iflet(NSString *z, y) {
            NSLog(@"y is not nil");
        }
        else {
            NSLog(@"y is nil");
        }
        
        ifletwhere(NSString *z, x, z.length < 100) {
            NSLog(@"x is not nil and < 100");
        }
        
        guard(3 < 2) else {
            NSLog(@"guard failed");
        }
        
        guardletwhere(NSString *z, x, z.length < 3) else {
            NSLog(@"guardletwhere failed");
        }
    }
}

/* outputs:
 
 iflet[57328:5182484] x is not nil
 iflet[57328:5182484] y is nil
 iflet[57328:5182484] x is not nil and < 100
 iflet[57328:5182484] guard failed
 iflet[57328:5182484] guardletwhere failed
 
 */