ReactiveCocoa的实际应用

1.监听方法执行

• 方法：rac_signalForSelector

[[v rac_signalForSelector:@selector(touchesBegan:withEvent:)] subscribeNext:^(id  _Nullable x) {
    NSLog(@"点击了我");
 }];

• 这个方法是创建对象中一定会调用的，所以在此方法中可以监听各个系统方法的执行，换了一种方式来写各个系统方法

+ (instancetype)allocWithZone:(struct _NSZone *)zone {
    ViewController *vc = [super allocWithZone:zone];
    // ViewDidLoad
    [[vc rac_signalForSelector:@selector(viewDidLoad)] subscribeNext:^(id  _Nullable x) {
        NSLog(@"ViewDidLoad");
    }];
    // ViewWillAppear
    [[vc rac_signalForSelector:@selector(viewWillAppear:)] subscribeNext:^(id  _Nullable x) {
        NSLog(@"ViewWillAppear");
    }];
    return vc;
}

2.监听按钮点击

• 方法：rac_signalForControlEvents

[[_button rac_signalForControlEvents:UIControlEventTouchDown] subscribeNext:^(id x) {
}];

3.监听文字的改变 ：(替代textField的代理)

• 方法：rac_textSignal

[_passWordTextField.rac_textSignal subscribeNext:^(id x) {
    _passWordLabel.text = x;
}];

• 方法：宏定义 RAC() 信号绑定

RAC(_passWordLabel, text) = _passWordTextField.rac_textSignal;

• 错误示范

//这样并不能获取textField的文字信号，获取的是textField本身的信号，写法错误
[[_passWordTextField rac_signalForControlEvents:UIControlEventValueChanged] subscribeNext:^(id x) {
    NSLog(@"%@", x);
    _passWordLabel.text = x; 
}];

4.代替KVO

• 方法：rac_valuesForKeyPath:@keypath(self, age) observer:self

    //方法默认监听新值和旧值
    [[self rac_valuesForKeyPath:@keypath(self, age) observer:self] subscribeNext:^(id x) {
        NSLog(@"0 - age = %d", self.age);
    }];

• 方法：rac_valuesAndChangesForKeyPath:@"age" options:NSKeyValueObservingOptionNew observer:self

    //按照选项监听新值或是旧值
    [[self rac_valuesAndChangesForKeyPath:@"age" options:NSKeyValueObservingOptionNew observer:self] subscribeNext:^(id x) {
        NSLog(@"1 - age = %d", self.age);
    }];

• 方法：rac_observeKeyPath:@"age" options:NSKeyValueObservingOptionNew observer:self block:

    //按照选项监听新值或是旧值
    [self rac_observeKeyPath:@"age" options:NSKeyValueObservingOptionNew observer:self block:^(id value, NSDictionary *change, BOOL causedByDealloc, BOOL affectedOnlyLastComponent) {
        NSLog(@"2 - age = %d", self.age);
    }];

• 方法：宏定义RACObserve()

//方法默认监听新值和旧值
[RACObserve(self, age) subscribeNext:^(id x) {
    NSLog(@"3 - age = %d", self.age);
}];

5.代替通知

• 方法：rac_addObserverForName

//不需要手动管理（移除）观察者
[[[NSNotificationCenter defaultCenter] rac_addObserverForName:@"Note" object:nil] subscribeNext:^(id x) {
    NSLog(@"%@", x);
}];
[[NSNotificationCenter defaultCenter] postNotificationName:@"Note" object:nil];

6.当某几个信号执行完毕再去调用一个方法（rac_liftSelector）

• 注意：有几个信号就必须有几个参数，参数就是订阅者发出的数据

    // 创建请求最热数据信号
    RACSignal *hotSignal = [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber>  _Nonnull subscriber) {
        // 请求最热数据
        [subscriber sendNext:@"最热数据"];
        return nil;
    }];
    // 创建请求最新数据信号
    RACSignal *newSignal = [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber>  _Nonnull subscriber) {
        // 请求最新的数据
        [subscriber sendNext:@"最新数据"];
        return nil;
    }];
    // Selector:当数组所有信号都发送next之后调用
    [self rac_liftSelector:@selector(updateUIWithHot:new:) withSignalsFromArray:@[hotSignal,newSignal]];