Thor – Cool Objective-C Bits, Libraries and Code Snippets [[TheSeries alloc] init];

Benjamin Van Der Veen (@bvanderveen) has been working with me to build out the Thor Application  based on Nathan Young’s (@nathanyoung) awesome designs. We’ll be releasing open source real soon. I wanted to cover some of the cool libraries, specific code snippets and such. These are a few of the things that have come in very useful as the coding deluge began.

Reactive Cocoa (AKA Reactive Extensions)

When you need to compose and transform sequences of values (kind of like Reactive Extensions for .NET) this is your library when working in Objective-C land. Reactive Cocoa or “RAC” for short can observe on key values to provide a key value for compliant properties. RAC helps to keep mutability under wraps (which is really really needed in Objective-C), pulls together behaviors and relationships between properties, and helps tremendously with asynchronous actions. The last bit we have a good amount of occurring with Thor since it talks to the Cloud Foundry web service API end points.

An example I snagged from the github site is below. It watches for changes on the username property.

[RACAbleSelf(self.username) subscribeNext:^(NSString *newName) {
    NSLog(@"%@", newName);
}];

Which serves, as pointed out in the README.md (be sure to read it if you’re going to use the library), as a wrapper around KVO. It goes on to show further sequences on complex actions.

[[[[RACAbleSelf(self.username)
    distinctUntilChanged]
    take:3]
    where:^(NSString *newUsername) {
        return [newUsername isEqualToString:@"joshaber"];
    }]
    subscribeNext:^(id _) {
        NSLog(@"Hi me!");
    }];

For some that write C# all the time this might seem like a “meh” moment. But considering the work that would be needed in Objective-C usually this could take significantly more lines of code, such as setting an observer, using a property or something to watch the value, monitor the non-distinct changes, and then bounce the value of the property for every non-distinct value. Yeah, and it still isn’t done. But anyway, that’s just the icing, the cake is delicious. If you’re in Objective-C land much, it is worth checking out.

Check it out on Github.