iOS 封装一个链式编程的应用框架

写一个能够实现连加（乘除减类似）

 n.add(10).add(20).add(30);
 n = 60;

首先写一个NSObject的分类，便于所有类都可调用：
通过分析Masonry

结构

- (NSArray *)mas_makeConstraints:(void(^)(MASConstraintMaker *))block；

我们可以定义此方法为：

+ (int)rr_makeConstraints:(void(^)(SumManager *manager))block；

SumManager就相当于MASConstraintMaker中的约束制造者
在这里担任加法管理者

SumManager.h

#import 

@interface SumManager : NSObject

/**  */
@property (nonatomic,assign) int result;

- (SumManager * (^)(int value))add;

@end

SumManager.m

#import "SumManager.h"

@implementation SumManager

- (SumManager * (^)(int value))add{

    return ^(int value){
    
        _result += value;
        
        return self;
        //返回一个“方法调用者”
    };
    
}

@end

NSObject+Sum.h

#import 
#import "SumManager.h"
@interface NSObject (Sum)

+ (int)rr_makeConstraints:(void(^)(SumManager *manager))block;

@end

NSObject+Sum.m

#import "NSObject+Sum.h"

@implementation NSObject (Sum)

+ (int)rr_makeConstraints:(void(^)(SumManager *manager))block{

    SumManager *mgr = [[SumManager alloc] init];
    
    block(mgr);
    
    return mgr.result;
    
}

@end

正式使用：ViewController.m

#import "ViewController.h"
#import "NSObject+Sum.h"
@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    int sum = [NSObject rr_makeConstraints:^(SumManager *manager) {
        
        manager.add(10).add(20).add(30);
        
    }];
    
    NSLog(@"sum == %d",sum);
    
    
}



- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


@end

输出结果：

2017-06-19 16:44:46.000 002-链式编程思想[3006:1593180] sum == 60