RAC 初學

1.給按鈕綁定方法

  [[self.button rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(id x) {
        NSLog(@"%@",x);
    }];

2.添加代理方法

    UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"RAC" message:@"RAC TEST" delegate:self cancelButtonTitle:@"CANCEL" otherButtonTitles:@"other", @"1111",@"2222",nil];
    [[self rac_signalForSelector:@selector(alertView:clickedButtonAtIndex:)fromProtocol:@protocol(UIAlertViewDelegate)]subscribeNext:^(RACTuple *tuple) {
        NSLog(@"tuple%@",tuple);
    }];

    [[alertView rac_buttonClickedSignal]subscribeNext:^(id x) {
        NSLog(@"%@",x);
    }];

3.接收通知

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

4.KVO

    UIScrollView *scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 300, 400, 300)];
    scrollView.backgroundColor = [UIColor redColor];
    scrollView.contentSize = CGSizeMake(0, 1000);
    [self.view addSubview:scrollView];
    
    [RACObserve(scrollView, contentOffset)subscribeNext:^(id x) {
        NSLog(@"%@",x);
    }];

MAP

映射的意思，就是創建一個訂閱者的映射并且返回數據
我理解為攔截到信號內容,返回想要的內容

    [[[self.button rac_signalForControlEvents:UIControlEventTouchUpInside]map:^id(id value) {
        NSLog(@"value: %@",value);
        return @"aaaa";
    }]subscribeNext:^(id x) {
        NSLog(@"x:%@",x);
    }];

輸出

2017-03-08 09:52:59.566726 RACDemo[6241:2176773] value: <UIButton: 0x1005113d0; frame = (20 154; 374 30); opaque = NO; autoresize = RM+BM; layer = <CALayer: 0x174039f40>>
2017-03-08 09:52:59.567147 RACDemo[6241:2176773] x:aaaa

filter 過濾

在 filter 中,如果返回 yes 則發送信號,no 則取消發送,達到過濾的效果

    [[self.textField.rac_textSignal filter:^BOOL(id value) {
        return [value length] > 3;
    }]subscribeNext:^(id x) {
        NSLog(@"x:%@",x);
    }];

輸出

2017-03-08 10:06:27.552855 RACDemo[6257:2180433] x:1111
2017-03-08 10:06:28.166590 RACDemo[6257:2180433] x:11111
2017-03-08 10:06:28.397429 RACDemo[6257:2180433] x:111111

take

選取前幾個信號進行發送
take 2 選取前兩個信號發送

    [[self.button rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(id x) {
        [self.textField endEditing:YES];
        //        [alertView show];
      
        //創建信號
        RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            [subscriber sendNext:@"1"];
            [subscriber sendNext:@"2"];
            [subscriber sendNext:@"3"];
            [subscriber sendNext:@"4"];
            [subscriber sendCompleted];
            return nil;
        }] take:2];
        
        //發送信號
        [signal subscribeNext:^(id x) {
            NSLog(@"x : %@",x);
        } completed:^{
            NSLog(@"completed");
        }];
        
        
    }];

輸出

2017-03-08 10:15:11.815895 RACDemo[6274:2184570] x : 1
2017-03-08 10:15:11.816197 RACDemo[6274:2184570] x : 2
2017-03-08 10:15:11.816323 RACDemo[6274:2184570] completed

skip

跳過信號
把上文中 take 替換成 skip
輸出:

2017-03-08 10:18:16.362060 RACDemo[6281:2185871] x : 3
2017-03-08 10:18:16.362506 RACDemo[6281:2185871] x : 4
2017-03-08 10:18:16.362658 RACDemo[6281:2185871] completed

repeat

把 take 2 替換成 repeat
信號會無限制的重復發送

相似的還有takeLast takeUntil takeWhileBlock skipWhileBlock skipUntilBlock repeatWhileBlock都可以根據字面意思來理解。

delay

延遲發送信號

        //創建信號
        RACSignal *signal = [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            [subscriber sendNext:@"1"];
            [subscriber sendNext:@"2"];
            [subscriber sendNext:@"3"];
            [subscriber sendNext:@"4"];
            [subscriber sendCompleted];
            return nil;
        }] delay:3]take:3];
        
        //發送信號
        [signal subscribeNext:^(id x) {
            NSLog(@"x : %@",x);
        } completed:^{
            NSLog(@"completed");
        }];

輸出

2017-03-08 10:24:25.470258 RACDemo[6294:2188587] x : 1
2017-03-08 10:24:25.470626 RACDemo[6294:2188587] x : 2
2017-03-08 10:24:25.470870 RACDemo[6294:2188587] x : 3
2017-03-08 10:24:25.471233 RACDemo[6294:2188587] completed

throttle

加了節流管道，后面跟上了類型為NSTimeInterval的參數后，只有0.5S內信號不產生變化才會發送請求，這樣快速的輸入也不會造成多次輸出。

[[[self.textFild rac_textSignal] throttle:0.5] subscribeNext:^(id x) {
    NSLog(@"%@", x);
}];

distinctUntilChanged

網絡請求中為了減輕服務器壓力，無用的請求我們應該盡可能不發送。distinctUntilChanged的作用是使RAC不會連續發送兩次相同的信號，這樣就解決了這個問題。

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

timeout

超時信號，當超出限定時間后會給訂閱者發送error信號

        //創建信號 延遲3秒發送,但是信號時限為2秒
        RACSignal *signal = [[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            [subscriber sendNext:@"1"];
            [subscriber sendNext:@"2"];
            [subscriber sendNext:@"3"];
            [subscriber sendNext:@"4"];
            [subscriber sendCompleted];
            return nil;
        }] delay:3]take:3]timeout:2 onScheduler:[RACScheduler mainThreadScheduler]];
        
        //發送信號
        [signal subscribeNext:^(id x) {
            NSLog(@"x: %@",x);
        } error:^(NSError *error) {
            NSLog(@"error : %@",error);
        }];

輸出

2017-03-08 10:32:32.149072 RACDemo[6302:2191123] error : Error Domain=RACSignalErrorDomain Code=1 "(null)"

ignore

忽略信號，指定一個任意類型的量（可以是字符串，數組等），當需要發送信號時講進行判斷，若相同則該信號會被忽略發送。

        //創建信號 take 3 發送三個信號,但是忽略內容為@"1"的信號
        RACSignal *signal = [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            [subscriber sendNext:@"1"];
            [subscriber sendNext:@"2"];
            [subscriber sendNext:@"3"];
            [subscriber sendNext:@"4"];
            [subscriber sendCompleted];
            
            return nil;
        }]take:3]ignore:@"1"];
        
        //發送信號
        [signal subscribeNext:^(id x) {
            NSLog(@"x: %@",x);
        } completed:^{
            NSLog(@"completed");
        }];

輸出

2017-03-08 10:38:36.399691 RACDemo[6313:2193199] x: 2
2017-03-08 10:38:36.400032 RACDemo[6313:2193199] x: 3
2017-03-08 10:38:36.400198 RACDemo[6313:2193199] completed

ignore 可以連續使用

        //創建信號
        RACSignal *signal = [[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            [subscriber sendNext:@"1"];
            [subscriber sendNext:@"2"];
            [subscriber sendNext:@"3"];
            [subscriber sendNext:@"4"];
            [subscriber sendCompleted];
            
            return nil;
        }]take:3]ignore:@"1"]ignore:@"2"];
        
        //發送信號
        [signal subscribeNext:^(id x) {
            NSLog(@"x: %@",x);

        } completed:^{
            NSLog(@"completed");
        }];

輸出

2017-03-08 10:39:07.841313 RACDemo[6316:2193759] x: 3
2017-03-08 10:39:07.841681 RACDemo[6316:2193759] completed

參拷貝:
http://www.lxweimin.com/p/ff79a5ae0353
http://www.lxweimin.com/p/aa155560bfed

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