1.一般編程

Calculate.h

#import <Foundation/Foundation.h>

@interface Calculate : NSObject
@property (nonatomic,assign) int result;
- (instancetype)add:(int)num;
@end

Calculate.m

#import "Calculate.h"

@implementation Calculate
- (instancetype)add:(int)num{
    _result += num;
    return self;
}
@end

ViewController.m

#import "ViewController.h"
#import "Calculate.h"

@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];
    
    Calculate *calculate = [Calculate new];
    int result = [[[[[[[calculate add:1] add:2] add:3] add:4] add:5] add:6] result];
    NSLog(@"result = %d",result);
    // 2016-08-14 17:15:13.444 Calculate[19636:1580250] result = 21
}
@end

2.函數(shù)式編程思想

函數(shù)式編程思想:把操作盡量寫(xiě)成一系列嵌套的函數(shù)或方法調(diào)用
函數(shù)式編程特點(diǎn):方法必須返回本身對(duì)象阱持，參數(shù)是block芝硬，該block的參數(shù)是需要操作的值，該block的返回值是操作的結(jié)果

Calculate.h

#import <Foundation/Foundation.h>
@interface Calculate : NSObject
@property (nonatomic,assign) int result;
- (instancetype)add:(int (^) (int result))block;
@end

Calculate.m

#import "Calculate.h"

@implementation Calculate
- (instancetype)add:(int (^) (int result))block{
    _result = block(_result);
    return self;
}
@end

ViewController.m

- (void)viewDidLoad{
    [super viewDidLoad];
    
    Calculate *calculate = [Calculate new];
    int result = [[calculate add:^int(int result) {
        result += 1;
        result += 2;
        result += 3;
        result += 4;
        result += 5;
        
        return result;
    }] result];
    NSLog(@"result = %d",result);
    // 2016-08-14 17:32:15.356 Calculate[21322:1595078] result = 15
}

3.函數(shù)化更進(jìn)一層

Calculate.h

#import <Foundation/Foundation.h>

@interface Calculate : NSObject
@property (nonatomic,assign) int result;
@property (nonatomic,assign) BOOL isEqual;
- (instancetype)add:(int (^) (int result))block;
- (instancetype)equal:(BOOL (^) (int result))block;
@end

Calculate.m

#import "Calculate.h"

@implementation Calculate
- (instancetype)add:(int (^) (int result))block{
    _result = block(_result);
    return self;
}

-(instancetype)equal:(BOOL (^)(int))block{
    _isEqual = block(_result);
    return self;
}
@end

ViewController.m

#import "ViewController.h"
#import "Calculate.h"

@implementation ViewController

- (void)viewDidLoad{
    [super viewDidLoad];
    
    Calculate *calculate = [Calculate new];
    BOOL isEqual = [[[calculate add:^int(int result) {
        result += 1;
        result += 2;
        result += 3;
        result += 4;
        result += 5;
        
        return result;
    }] equal:^BOOL(int result) {
        return (result == 15);
    }] isEqual];
    NSLog(@"isEqual = %d",isEqual);
    // 2016-08-14 17:47:29.657 Calculate[22823:1608283] isEqual = 1
}
@end