DRBlocks

Convenient way to work with multiple blocks in Objective-C. DRBlocks is a Key-ValueArray store for blocks. Adding multiple blocks for the same key will append them to the same key's ValueArray. This could be useful if you need to store multiple completion blocks while an asyncronous event is finishing, and then calling each of the those blocks when the event finishes.

Using DRBlocks in your App

Add a blocks to DRBlocks.

[[DRBlocks sharedBlocks] addBlock:^(NSString *a, NSString *b) {

  NSLog(@"Block 1: %@ %@", a, b);

} forKey:@"test"];

[[DRBlocks sharedBlocks] addBlock:^(NSString *a, NSString *b) {

  NSLog(@"Block 2: %@ %@", a, b);

} forKey:@"test"];
    

Consuming the blocks is easy. You call consumeBlocksForKey:handler: and you will be given each block. Then, just call the block with the parameters you need to pass to it.

[[DRBlocks sharedBlocks] consumeBlocksForKey:@"test" handler:^(NSString *a, NSString *b block) {

  // call your block! Gaurenteed not to be nil.
  block(@"hello",@"world");

}];

Reason for Existence

Sometimes you design an Obj-C class that needs to store multiple blocks which will be called at a later time. For example, you design a location manager that calls blocks when the user's location has been determined:

- (void)getUserLocationWithCompletion:(void (^)(CLLocation *location, NSError * error))blockName;

To properly implement the above method, you need to support the case where getUserLocationWithCompletion: is called many times before the location is determined. Internally, you will probably create an NSMutableArray and add each block to the array.

When the user's location is finally know, you will enumerate the array of pending completion blocks and call each one, and then finally remove the blocks from the array.

I have used this design pattern enough times that I decided it was time to create an CocoaPod that handles all of this for me.

Installation with CocoaPods

Not yet submitted to Cocoapods. Use the direct git URL

CocoaPods is a dependency manager for Objective-C. See the "Getting Started" guide for more information.

pod "DRBlocks", :git => 'git@github.com:objectiveSee/DRBlocks.git', :commit => '851ff77b2f067c18d45d93eddd18ee8239f5d632'

If you don't use CocoaPods, reconsider using them or add DRBlocks.h and DRBlocks.m to your project.

Feedback

Contact me via Twitter @topwobble