1. 鏈?zhǔn)骄幊趟枷?/h3>

鏈?zhǔn)骄幊趟枷氲暮诵木褪?strong>方法的返回值必須是Block，Masonry是鏈?zhǔn)骄幊趟枷霊?yīng)用的代表。

1.1 Masonry應(yīng)用鏈?zhǔn)骄幊趟枷朐斀?/h3>

    UIView *redView = [[UIView alloc] init];
    redView.backgroundColor = [UIColor redColor];
    [self.view addSubview:redView];

    /**
     給控件設(shè)置布局,把控件的所有約束保存到約束制造者中.

     1.創(chuàng)建一個(gè)約束制造者
     2.調(diào)用block(maker),把所有的控件的約束全部保存到約束制造者
     3.[constraintMaker install]:遍歷約束制造者的所有約束給控件添加約束
     
     @param make 約束制造者
     @return MASConstraint
     */
    [redView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.top.equalTo(@10);
        make.right.bottom.equalTo(@(-10));
    }];

1.2 鏈?zhǔn)骄幊趟枷霊?yīng)用---計(jì)算器

@interface CaculatorMaker : NSObject

@property (nonatomic, assign) int result;

- (instancetype)add:(int)num; 

- (CaculatorMaker *(^)(int num))add;
- (CaculatorMaker *(^)(int))sub;
- (CaculatorMaker *(^)(int num))multy;
- (CaculatorMaker *(^)(int))divide;

@end

@implementation CaculatorMaker

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

- (CaculatorMaker * (^)(int num))add
{
    return ^(int num){
        _result += num;
        return self;
    };
}

@end

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

@interface NSObject (Caculator)

// 以后計(jì)算都使用這個(gè)方法,一調(diào)用這個(gè)方法就返回結(jié)果.
+ (int)makeCaculator:(void(^)(CaculatorMaker *))block;

@end

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

@implementation NSObject (Caculator)
+ (int)makeCaculator:(void (^)(CaculatorMaker *))block
{
    // 創(chuàng)建計(jì)算制造者
    CaculatorMaker *maker = [[CaculatorMaker alloc] init];
    // 計(jì)算
    block(maker);
    
    return maker.result;
}
@end

    // 1.創(chuàng)建計(jì)算制造者
    CaculatorMaker *maker = [[CaculatorMaker alloc] init];
    
    // 提供一個(gè)沒參數(shù)的add方法,返回值block
    int reslut1 = [[[[[maker add:10] add:20] add:30] add:40] result];
    
    // block:使代碼高聚合
    int result2 = [NSObject makeCaculator:^(CaculatorMaker *maker) {
        // 把所有的計(jì)算代碼封裝到這里
        maker.add(10).add(20);
        maker.multy(3);
    }];
    
    NSLog(@"%d",result2);

之前開發(fā)中比較習(xí)慣把事情封裝到一個(gè)方法中,鏈?zhǔn)骄幊趟枷?把要做的事情封裝到block,給外界提供一個(gè)返回這個(gè)Block的方法。

鏈?zhǔn)骄幊趟枷敕椒ㄌ攸c(diǎn):

方法返回值必須是block
block參數(shù):放需要操作的內(nèi)容
block返回值:方法調(diào)用者

2. 響應(yīng)式編程思想

不需要考慮調(diào)用順序，只需要知道考慮結(jié)果，類似于蝴蝶效應(yīng)，產(chǎn)生一個(gè)事件，會(huì)影響很多東西，這些事件像流一樣的傳播出去，然后影響結(jié)果，借用面向?qū)ο蟮囊痪湓挘f物皆是流。代表有KVO的運(yùn)用。

模仿系統(tǒng)提供的KVO：

@interface Person : NSObject
{
    @public
    int _age;
}
@property (nonatomic, assign) int age;

@end

@implementation Person

@end

@interface LLKVONotifying_Person : Person

@end

#import "LLKVONotifying_Person.h"
#import <objc/runtime.h>

@implementation LLKVONotifying_Person
- (void)setAge:(int)age
{
    [super setAge:age];
    
    // 通知觀察者,屬性改變
    id observer = objc_getAssociatedObject(self, @"observer");
    
    [observer observeValueForKeyPath:@"age" ofObject:self change:nil context:nil];
}
@end

@interface NSObject (KVO)

- (void)LL_addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(nullable void *)context;

@end

#import "NSObject+KVO.h"
#import "LLKVONotifying_Person.h"
#import <objc/runtime.h>

@implementation NSObject (KVO)
- (void)LL_addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(void *)context
{
    // 1.動(dòng)態(tài)創(chuàng)建NSKVONotifying_Person,NSKVONotifying_Person是Person子類,做KVO
    // 2.修改當(dāng)前對(duì)象的isa指針->NSKVONotifying_Person
    // 3.只要調(diào)用對(duì)象的set,就會(huì)調(diào)用NSKVONotifying_Person的set方法
    // 4.重寫NSKVONotifying_Person的set方法,1.[super set:] 2.通知觀察者,告訴你屬性改變
    
    // 修改isa,本質(zhì)就是改變當(dāng)前對(duì)象的類名
    object_setClass(self, [LLKVONotifying_Person class]);
    
    // 把觀察者保存到當(dāng)前對(duì)象里
    
    // 添加關(guān)聯(lián)
    // id object:給哪個(gè)對(duì)象添加關(guān)聯(lián)屬性
    // key:屬性名
    // value:關(guān)聯(lián)值
    objc_setAssociatedObject(self, @"observer", observer, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end

@interface ViewController ()

@property (nonatomic, strong) Person *p;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    Person *p = [[Person alloc] init];
    _p = p;

    // 添加觀察者
    //[p addObserver:self forKeyPath:@"age" options:NSKeyValueObservingOptionNew context:nil];
    [p LL_addObserver:self forKeyPath:@"age" options:NSKeyValueObservingOptionNew context:nil];
}

// 監(jiān)聽的屬性只要一改變就調(diào)用
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context
{
    NSLog(@"%d",_p.age);
}

KVO底層實(shí)現(xiàn):

1.動(dòng)態(tài)創(chuàng)建NSKVONotifying_Person,NSKVONotifying_Person是Person子類,做KVO
2.修改當(dāng)前對(duì)象的isa指針->NSKVONotifying_Person
3.只要調(diào)用對(duì)象的set,就會(huì)調(diào)用NSKVONotifying_Person的set方法
4.重寫NSKVONotifying_Person的set方法,1.[super set:] 2.通知觀察者,告訴你屬性改變

KVO的實(shí)質(zhì)就是去判斷有沒有調(diào)用一個(gè)對(duì)象的set方法。

3. 函數(shù)式編程思想

其實(shí)就是把操作盡量寫成一系列嵌套的函數(shù)或者方法調(diào)用。

特點(diǎn)：每個(gè)方法必須有返回值（本身對(duì)象）,把函數(shù)或者Block當(dāng)做參數(shù),block參數(shù)（需要操作的值）block返回值（操作結(jié)果）

利用函數(shù)式編程寫一個(gè)加法計(jì)算器,并且加法計(jì)算器自帶判斷是否等于某個(gè)值。

@interface Caculator : NSObject

@property (nonatomic, assign) int result;
@property (nonatomic, assign) BOOL isEqule;

- (instancetype)add:(int(^)(int result))block;
- (instancetype)equle:(BOOL(^)(int result))block;

@end


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

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

    Caculator *caculator = [[Caculator alloc] init];
    BOOL isEqule = [[[caculator add:^(int result){
        // 把計(jì)算的事情寫到Block
        
        result += 10;
        result += 20;
        result += 30;
        result += 40;
        
        return result;
        
    }] equle:^BOOL(int result) {
        
        return result == 100;
    }] isEqule];

函數(shù)式編程的代表是：ReactiveCocoa，在下一篇中我們會(huì)詳細(xì)討論ReactiveCocoa。