Blocks, note

Blocks

1. Thread blocking.

2. Statement block, similar to the function pointer in C language.

(Note !!) 3. Memory cyclic reference: blocks reserves a strong pointer reference for the objects in the starting statement block. If the object also retains a strong pointer reference for the block, it will be applied cyclically, so that both objects cannot be released from the heap.

 

Applicable blocks:

1, enumeration. enumeration.

2. view animation. uiview.

3. Sorting. sort.

4. Notification. event.

5, error handlers.

6, completion handlers.

7 (most important): multi-core multi-thread (GCD), Standard c api form, and UI-related operations are all executed in the main thread.