JSON Safe

Set of categories on Foundation objects that simplify your life while working on parsed JSON objects.

Why?

Typical workflow while working with JSON looks like this:

NSError *error      = nil;
NSData  *JSONData   = [self populateJSONData];
id       JSONObject = [NSJSONSerialization JSONObjectWithData:JSONData options:0 error:&error];
Class expectedClass = [NSDictionary class];

if ([JSONObject isKindOfClass:expectedClass]) {
    [self processJSONDictionary:(NSDictionary *)JSONObject];
}

You see? All your code is scattered with -isKindOfClass:. This protects your app from crashes when JSON data changes a bit. However in a JSON heavy application these cast operations produce a lot of unnecessary noice and you can't read your code fluently.

That's why JSON Safe was created. You can work with your JSON safely:

// produces NSDictionary or nil if there was no NSDictionary parsed
NSDictionary *JSONDict = [JSONObject mr_toDictionary];

Example Usage

Following conversions of an arbitrary JSON object are supported:

• to NSString
• to NSNumber
• to NSArray
• to NSArray of items of specified class
• to NSDictionary

NSNull always gets converted to nil, no matter what are you trying to get: NSString, NSNumber, NSArray or NSDictionary.

Attempt to convert NSNumber to NSNumber yield same object. To NSString — invoke -[NSNumber stringValue]. To NSArray — produce NSArray containing the receiver. To NSDictionary — nil.

Similar things happen with NSString:

• NSString → NSString gives the same object
• → NSNumber uses NSNumberFormatter with decimal separator set to .
• → NSArray yields to @[ self ]
• → NSDictionary returns nil

A bit tricky stuff happens with NSArray and NSDictionary. Here are NSArray conversion rules:

• Conversion from NSArray to NSString gives you concatenated\n\content\nof\nthe\narray
• To NSNumber outcomes in nil
• → NSArray yields self
• → NSDictionary — nil

And finally NSDictionary:

• Attempt to convert it to non collection object will result in nil
• → NSArray results @[ self ]
• → NSDictionary — self

The project is covered with set of tests that act like documentation. Go check it in tests/ directory.

Installation

Add following lines to your Podfile:

pod 'MRJSONSafe'

Then run pod install.

Or just copy src/MRJSONSafe.h and src/MSJSONSafe.m to your project if you don't bother to use CocoaPods.

Author

The original idea was developed by Michael Efimov while working on Yandex.Search for iPhone application. Currently the project is maintained by Roman Busyghin.

Contributing

Want something to be changed? Clone repo, write code, tests and documentation then submit pull request.

License

MRJSONSafe is available under the MIT license. See the LICENSE file for more info.