How does typedef-ing a block works
See Declaring a Block Reference in "Blocks Programming Topics":
Block variables hold references to blocks. You declare them using syntax similar to that you use to declare a pointer to a function, except that you use ^ instead of *.
So
typedef void (^myBlock) (int a);defines a the type of a block using the same syntax as
typedef void (*myFunc) (int a);declares a function pointer.
See e.g. Understanding typedefs for function pointers in C for more information about function pointers.
Also from "Blocks Programming Topics", creating a type for blocks should be like this:
typedef returnType (^blockName)(argument1, argument2, ...)Below is a very simple practical example:
typedef float (^MyBlockType)(float, float);MyBlockType AddTwoFloat = ^(float a, float b) {return a + b;};MyBlockType MultiplyTwoFloat = ^(float a, float b) {return a * b;};float c = AddTwoFloat(1, 2); //c = 3float d = MultiplyTwoFloat(1, 2); //d = 2