Adapters

You can pass a dictionary of blocks for field requiring special handling. Say a service sends back a dictionary that looks something like this:

{
    "favorite_color": [
        122,
        50,
        80
    ],
    "least_favorite_color": [
        121,
        51,
        81
    ]
}

and we expect to map it to a model like this

@interface MYModel : NSObject
@property (nonatomic, strong) UIColor *favoriteColor;
@property (nonatomic, strong) UIColor *leastFavoriteColor;
@end

You can adapt the response with an adapter block:

OHMMappable([MYModel class]);
OHMSetMapping([MYModel class], @"least_favorite_color" : @"leastFavoriteColor", @"favorite_color" : @"favoriteColor")
OHMValueAdapterBlock colorFromNumberArray = ^(NSArray *numberArray) {
    return [UIColor colorWithRed:[numberArray[0] integerValue]/255.0
                           green:[numberArray[1] integerValue]/255.0
                            blue:[numberArray[2] integerValue]/255.0
                           alpha:1];
};
OHMSetAdapter([MYModel class], @{@"favoriteColor": colorFromNumberArray, @"leastFavoriteColor": colorFromNumberArray});

Note that the key for the adapter is the key on the model object, not on the response. And adapters are added for a property, not a type. If the above example had multiple properties that were colors, you would have to set an adapter block for each property. It would be smart to reuse adapter blocks in your code.

The OHMValueAdapterBlock type is a block that takes an id and returns an id. i.e typedef id(^OHMValueAdapterBlock)(id);