Removes each key/value in another given dictionary from the receiving dictionary, if present.

NSMutableDictionary+Minus.h

#import <Foundation/Foundation.h>

@interface NSMutableDictionary (Minus)

-(void) minusDictionary:(NSDictionary*)otherDictionary;

@end

NSMutableDictionary+Minus.m

#import "NSMutableDictionary+Minus.h"

@implementation NSMutableDictionary (Minus)

-(void) minusDictionary:(NSDictionary*)otherDictionary{
    NSMutableSet *setA = [NSMutableSet setWithArray:self.allKeys];
    NSMutableSet *setB = [NSMutableSet setWithArray:otherDictionary.allKeys];
    // Get the right keys to remove
    [setA intersectSet:setB];
    [self removeObjectsForKeys:setA.allObjects];
}

@end