block简单回顾

block ：是一个指向结构体的指针。可暂时保存代码块。

1.带参数or返回值

 // 1.带参数的block
    void (^oneblock)(int) =  ^(int numberLine){ // 存储代码
        for (int i = 0; i < numberLine; i++) {
            NSLog(@"****");
        }
    };
    oneblock(3);
    
    // 2.带返回值的block
    int (^twoblock)() = ^{
        int a = 10, b = 10;
        return a + b;
    };
    int twoblockResult =  twoblock();
    NSLog(@"result = %d", twoblockResult);
    
    // 3.带参数和返回值
    int (^threeblock)(int, int) =  ^(int a, int b ){
        return a + b;
    };
    int threeblockResult =  threeblock(1024,1024);
    NSLog(@"threeblockResult = %d", threeblockResult);

2.typedef简化声明

typedef int (^typedefBlock)(int, int);

void testtypedefBlock()
{
    typedefBlock result  = ^(int a, int b){
        return  a + b;
    };
    
    int typedefresult = result(10, 10);
    NSLog(@"typedefresult = %d",typedefresult );
}

3.block参数传递

void gotowork(void (^mytodaywork)())
{
    NSLog(@"起床");
    mytodaywork();
    NSLog(@"回家");
    
}
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        gotowork(^{
            NSLog(@"去公司熟悉下代码");
        });
        
        gotowork(^{
            NSLog(@"完成实现功能");
        });
    }
    return 0;
}