一、Block Overview

1. Definition of Block

In iOS development, a Block is a closure - like construct that encapsulates a segment of code. It can be passed and stored as an object (similar to a function pointer). Blocks can capture variables from their defining scope, so the code within can execute with acess to those variables later. This makes them very suitable for callbacks, asynchronous operations, and event handling.

2. Rationale for Introducing Blocks

Blocks are essentially objects that package code. iOS introduces them to simplify code and reduce coupling, as they allow for a cleaner and more modular implementation of asynchronous or callback - based logic.

二、Using Blocks

2.1 As a Variable

int (^multiplyBlock)(int, int) = ^(int x, int y) {
    return x * y;
};
int product = multiplyBlock(4, 6); // Invoke the Block

2.2 As a Method Parameter

- (void)executeBlock:(void (^)(void))actionBlock {
    actionBlock();
}
[self executeBlock:^{ 
    NSLog(@