block

///变量

@property (nonatomic,copy,nullable) int (^blockName2) (int,int);

self.blockName2 = ^ int (int a,int b){

return a+b;

};

int a = self.blockName2(2,3);

///定义成参数

int (^blockName)(int) = ^ int (int a){

a += 10;

NSLog(@"block");

return a;

};

[self methodBlock:blockName];

[self methodBlock:^int(int a) {

a+=20;

NSLog(@"block2");

return a;

}];

///当成参数传来

-(void)methodBlock:(int (^)(int a)) blockName{

int a =  blockName(2);

NSLog(@"a=%d",a);

}