链式编程思想:把要做的事情封装到block,给外界提供一个返回这个Block的方法
链式编程思想方法特点:方法返回值必须是block,block参数:放需要操作的内容,block返回值:方法调用者

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface CaculatorMaker : NSObject
@property (nonatomic, assign) int result;

// +
- (CaculatorMaker *(^)(CGFloat num))add;
// -
- (CaculatorMaker *(^)(CGFloat num))subtract;
// *
- (CaculatorMaker *(^)(CGFloat num))multy;
// ÷
- (CaculatorMaker *(^)(CGFloat num))divide;


#import "CaculatorMaker.h"

@implementation CaculatorMaker
- (CaculatorMaker * (^)(CGFloat num))add
{
    return ^(CGFloat num){
      
        _result += num;
        
        return self;
    };
}
- (CaculatorMaker *(^)(CGFloat))subtract
{
    return ^(CGFloat num){
        
        _result -= num;
        
        return self;
    };
}
- (CaculatorMaker *(^)(CGFloat))multy
{
    return ^(CGFloat num){
        
        _result *= num;
        
        return self;
    };
}
- (CaculatorMaker *(^)(CGFloat))divide
{
    return ^(CGFloat num){
        
        _result = _result/num;
        
        return self;
    };
}
@end

#import <Foundation/Foundation.h>
#import "CaculatorMaker.h"

@interface NSObject (Caculator)

// 以后计算都使用这个方法,一调用这个方法就返回结果.
+ (CGFloat)makeCaculator:(void(^)(CaculatorMaker *))block;
@end

#import "NSObject+Caculator.h"
#import "CaculatorMaker.h"

@implementation NSObject (Caculator)
+ (CGFloat)makeCaculator:(void (^)(CaculatorMaker *))block
{
    // 创建计算制造者
    CaculatorMaker *maker = [[CaculatorMaker alloc] init];
    // 计算
    block(maker);
    return maker.result;
}
@end

调用

#import "ViewController.h"
#import "CaculatorMaker.h"
#import "NSObject+Caculator.h"
@interface ViewController ()
@end

@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    
    // block:使代码高聚合
    CGFloat result = [NSObject makeCaculator:^(CaculatorMaker *maker) {
        
        // 把所有的计算代码封装到这里
        maker.add(10).add(20);
        maker.add(30).add(40);
        maker.multy(3);
        maker.divide(10);
    }];
    
    NSLog(@"%.2f",result);
}