响应式编程思想(一)

以KVO为例做了一个简单的响应式编程demo，特此记。

KVO的底层实现就是监听属性值set方法的改变。

需要创建一下几个文件。

• Person

Person.h

#import <Foundation/Foundation.h>@interface Person : NSObject/** age */@property(nonatomic,assign)NSInteger age;@end

Person.m

#import "Person.h"@implementation Person@end

• KVO_Person

KVO_Person.h

#import "Person.h"@interface KVO_Person : Person@end

KVO_Person.m

#import "KVO_Person.h"#import "NSObject+zw_Kvo.h"#import <objc/runtime.h>@implementation KVO_Person-(void)setAge:(NSInteger)age{    [super setAge:age];     //发通知    id obsver = objc_getAssociatedObject(self, @"obsever");    id keypath = objc_getAssociatedObject(self, @"keyPath");    [obsver observeValueForKeyPath:keypath ofObject:nil change:nil context:nil];}@end

• NSObject+zw_Kvo

NSObject+zw_Kvo.h

#import <Foundation/Foundation.h>@interface NSObject (zw_Kvo)- (void)zw_addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(nullable void *)context;@end

NSObject+zw_Kvo.m

#import "NSObject+zw_Kvo.h"#import "KVO_Person.h"#import <objc/runtime.h>@implementation NSObject (zw_Kvo)- (void)zw_addObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(nullable void *)context{     //修改对象指针    object_setClass(self, [KVO_Person class]);    //保存可以    objc_setAssociatedObject(self, @"obsever", observer, OBJC_ASSOCIATION_RETAIN_NONATOMIC);     objc_setAssociatedObject(self, @"keyPath", keyPath, OBJC_ASSOCIATION_RETAIN_NONATOMIC);}@end

ZWKVOViewController

ZWKVOViewController.m

#import "ZWKVOViewController.h"#import "Person.h"#import "NSObject+zw_Kvo.h"@interface ZWKVOViewController ()@property(nonatomic,strong) Person *person;@end@implementation ZWKVOViewController- (void)viewDidLoad {    [super viewDidLoad];    self.title = @"响应式编程实现KVO";    [self method2];}-(void)method2{    //实现KVO 就是监听set方法    Person *person = [[Person alloc]init];    [person zw_addObserver:self forKeyPath:@"age" options:NSKeyValueObservingOptionNew context:nil];    self.person    = person;}-(void)method1{    //实现KVO 就是监听set方法    Person *person = [[Person alloc]init];    [person addObserver:self forKeyPath:@"age" options:NSKeyValueObservingOptionNew context:nil];    self.person    = person;}-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context{    NSLog(@"age==>");}-(void)viewWillDisappear:(BOOL)animated{    [super viewWillDisappear:animated];    [self.person removeObserver:self forKeyPath:@"age"];}-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{    self.person.age ++;}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end