Links

• Episode Source Code
• Careful with Block Based Notification Handlers - This is a blog post I wrote which indicates a small gotcha you have to be aware of when dealing with blocks.
• Concurrency Programming Guide - Apple's documentation on using blocks with GCD (Grand Central Dispatch) to make multi-threaded code much easier to read & write.

Creating a Block with no Arguments

^ {
  // block code here
}

Using a block as a method parameter

If you want to accept a block as a method parameter, you can type out the cryptic syntax, but it's not very easy to read (or write).

This method accepts a block. The block accepts a BOOL parameter and must return an NSString.

- (void)someMethodWithBlock:(NSString * (^)(BOOL))block;

To make this more usable elsewhere in the code, you can use a typedef instead. Put this somewhere in your header file:

typedef NSString * (^CrazyBlock)(BOOL animated);

Then you can update where it's used:

- (void)someMethodWithBlock:(CrazyBlock)block;