RAC与Target-Action、通知、代理、KVO

ReactiveCocoa作用
1.target-action:rac_signalForControlEvents
rac_textSignal rac_gestureSignal
2.代理 rac_signalForSelector:@selector() fromProtocol:()

3.通知 rac_addObserverForName
4.KVO RACObserve(object, value)

代码示例：
1.target-action

//1.1 监听textfield文字更改
[[self.textfiled rac_signalForControlEvents:UIControlEventEditingChanged] subscribeNext:^(id x){
    NSLog(@"change");
}];

//简写
[[self.textfiled rac_textSignal] subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];

//1.2
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];
    [[tap rac_gestureSignal] subscribeNext:^(id x) {
    NSLog(@"tap");
}];
//注意：如果给label添加手势，需要打开userInteractionEnabled
self.lab.userInteractionEnabled = YES;
[self.lab addGestureRecognizer:tap];

2.代理：rac_signalForSelector:@selector() fromProtocol:()
*** 注意：只能实现返回值为void的代理方法

UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"title" message:@"rac test" delegate:self cancelButtonTitle:@"no" otherButtonTitles:@"yes", nil];
    [[self rac_signalForSelector:@selector(alertView:clickedButtonAtIndex:) fromProtocol:@protocol(UIAlertViewDelegate)] subscribeNext:^(RACTuple *tuple) {
        //tuple为点击按钮的各个参数
        NSLog(@"%ld",tuple.count);    //参数个数 2 
        NSLog(@"%@",tuple.first);     //alertView
        NSLog(@"%@",tuple.second);    //buttonIndex
        NSLog(@"%@",tuple.third);     //null
    }];
//简写
[[alertView rac_buttonClickedSignal] subscribeNext:^(id x) {
    NSLog(@"%@",x);     //buttonIndex
}];
[alertView show];

3.通知 rac_addObserverForName
点击一个页面可以更新另一个页面数据

[[[NSNotificationCenter defaultCenter] rac_addObserverForName:@"postData" object:nil] subscribeNext:^(NSNotification *notification) {
    NSLog(@"%@", notification.name);
    NSLog(@"%@", notification.object);
}];

[self presentViewController:[[SecondViewController alloc]init] animated:YES completion:nil];

SecondViewController代码：

NSMutableArray *dataArray = [[NSMutableArray alloc] initWithObjects:@"1", @"2", @"3", nil];
[[NSNotificationCenter defaultCenter] postNotificationName:@"postData" object:dataArray];
[self dismissViewControllerAnimated:YES completion:nil];

4.KVO RACObserve(object, value)

UIScrollView *scrolView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 300, 200, 400)];
scrolView.contentSize = CGSizeMake(200, 800);
scrolView.backgroundColor = [UIColor greenColor];
[self.view addSubview:scrolView];
[RACObserve(scrolView, contentOffset) subscribeNext:^(id x) {
    NSLog(@"success");
}];

原文链接：学习RAC小记-适合给新手看的RAC用法总结