Set the same value for all existing keys in an NSDictionary

Question

In KVC, I usually use setValues:forKeyPath: to set the same value for objects in a collection. E.g.:

NSMutableArray <SomeClass *> *arr = [[NSMutableArray alloc] initWithCapacity:10];
for (int i = 0; i < 10; i++) {
    SomeClass *obj = [[SomeClass alloc] init];
    obj.stringProp = @(i).stringValue;
    [arr addObject:obj];
}

NSLog(@"- %@", [arr valueForKeyPath:@"stringProp"]);
[arr setValuesForKeysWithDictionary:@{@"stringProp" : @"Same same!"}];

NSLog(@"- %@", [arr valueForKeyPath:@"stringProp"]);
[arr setValue:@"Another" forKeyPath:@"stringProp"];

NSLog(@"- %@", [arr valueForKeyPath:@"stringProp"])

But, for a dictionary, can we use that as well? Now I've gotta set values manually:

NSMutableDictionary *myDict;
//... setupValues
NSString *valueToSet = @"Hehe";
for (NSString *key in myDict) {
    [myDict setObject:valueToSet forKey:key];
}

Is there a simple solution for a dictionary, like the example above?

Answer 1

I'm not sure if there is a function for that (I guess it don't), but in case you gonna need to do that multiple times, you can add a function to NSMutableDictionary to help you with that:

@interface NSMutableDictionary (NSMutableDictionarySetAllKeysObject)
-(void)setAllKeysObject:(nonnull id)object;
@end

@implementation NSMutableDictionary (NSMutableDictionarySetAllKeysObject)
-(void)setAllKeysObject:(nonnull id)object
{
    for (NSString *key in self.allKeys) {
        [self setObject:object forKey:key];
    }
}
@end

So you would be able to do that:

NSString *valueToSet = @"Hehe";
[myDict setAllKeysObject:valueToSet];