ReactiveCocoa初步

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

打印结果

2013-12-24 14:48:50.359 RWReactivePlayground[9193:a0b] i
2013-12-24 14:48:50.436 RWReactivePlayground[9193:a0b] is
2013-12-24 14:48:50.541 RWReactivePlayground[9193:a0b] is
2013-12-24 14:48:50.695 RWReactivePlayground[9193:a0b] is t
2013-12-24 14:48:50.831 RWReactivePlayground[9193:a0b] is th
2013-12-24 14:48:50.878 RWReactivePlayground[9193:a0b] is thi
2013-12-24 14:48:50.901 RWReactivePlayground[9193:a0b] is this
2013-12-24 14:48:51.009 RWReactivePlayground[9193:a0b] is this
2013-12-24 14:48:51.142 RWReactivePlayground[9193:a0b] is this m
2013-12-24 14:48:51.236 RWReactivePlayground[9193:a0b] is this ma
2013-12-24 14:48:51.335 RWReactivePlayground[9193:a0b] is this mag
2013-12-24 14:48:51.439 RWReactivePlayground[9193:a0b] is this magi
2013-12-24 14:48:51.535 RWReactivePlayground[9193:a0b] is this magic
2013-12-24 14:48:51.774 RWReactivePlayground[9193:a0b] is this magic?

rac_textSignal文本信号订阅，传递给下一个，打印

文本信号过滤（长度过滤）filter:

filter:^BOOL(id value) {
    NSString *text = value;
    return text.length > 3;
  }]

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

打印结果

2013-12-26 08:17:51.335 RWReactivePlayground[9654:a0b] is t
2013-12-26 08:17:51.478 RWReactivePlayground[9654:a0b] is th
2013-12-26 08:17:51.526 RWReactivePlayground[9654:a0b] is thi
2013-12-26 08:17:51.548 RWReactivePlayground[9654:a0b] is this
2013-12-26 08:17:51.676 RWReactivePlayground[9654:a0b] is this
2013-12-26 08:17:51.798 RWReactivePlayground[9654:a0b] is this m
2013-12-26 08:17:51.926 RWReactivePlayground[9654:a0b] is this ma
2013-12-26 08:17:51.987 RWReactivePlayground[9654:a0b] is this mag
2013-12-26 08:17:52.141 RWReactivePlayground[9654:a0b] is this magi
2013-12-26 08:17:52.229 RWReactivePlayground[9654:a0b] is this magic
2013-12-26 08:17:52.486 RWReactivePlayground[9654:a0b] is this magic?

可见大于三个的输入才会把输入的文本信号传递给订阅者

代码整理一下

RACSignal *usernameSourceSignal =
    self.usernameTextField.rac_textSignal;

RACSignal *filteredUsername = [usernameSourceSignal
  filter:^BOOL(id value) {
    NSString *text = value;
    return text.length > 3;
  }];

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

订阅信号，过滤条件，传递给订阅者

[[self.usernameTextField.rac_textSignal
  filter:^BOOL(id value) {
    NSString *text = value; // implicit cast
    return text.length > 3;
  }]
  subscribeNext:^(id x) {
    NSLog(@"%@", x);
  }];

关于id value,在此例中就是传递的字符串

可直接修改替换

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

rac_textSignal默认传递给订阅者的是文本内容，想传递其他的内容需要用到map

map:^id(NSString *text) {
    return @(text.length);
  }]

[[[self.usernameTextField.rac_textSignal
  map:^id(NSString *text) {
    return @(text.length);
  }]
  filter:^BOOL(NSNumber *length) {
    return [length integerValue] > 3;
  }]
  subscribeNext:^(id x) {
    NSLog(@"%@", x);
  }];

传递给订阅者文本长度信号，再对这个信号进行了文本长度大于3的过滤器，最近订阅者终于订阅到了这个实时的文本输入长度信号

2013-12-26 12:06:54.566 RWReactivePlayground[10079:a0b] 4
2013-12-26 12:06:54.725 RWReactivePlayground[10079:a0b] 5
2013-12-26 12:06:54.853 RWReactivePlayground[10079:a0b] 6
2013-12-26 12:06:55.061 RWReactivePlayground[10079:a0b] 7
2013-12-26 12:06:55.197 RWReactivePlayground[10079:a0b] 8
2013-12-26 12:06:55.300 RWReactivePlayground[10079:a0b] 9
2013-12-26 12:06:55.462 RWReactivePlayground[10079:a0b] 10
2013-12-26 12:06:55.558 RWReactivePlayground[10079:a0b] 11
2013-12-26 12:06:55.646 RWReactivePlayground[10079:a0b] 12

当我们需要用一个方法来判断输入的用户名或者密码符合要求不，一般会写个额外的方法，然后在这个方法里进行正则匹配。

那么 我们就要用这个方法来处理最初默认的文本内容信号

RACSignal *validUsernameSignal =
  [self.usernameTextField.rac_textSignal
    map:^id(NSString *text) {
      return @([self isValidUsername:text]);
    }];

RACSignal *validPasswordSignal =
  [self.passwordTextField.rac_textSignal
    map:^id(NSString *text) {
      return @([self isValidPassword:text]);
    }];

根据这个NSNumber来传递一个UIColor

[[validPasswordSignal
  map:^id(NSNumber *passwordValid) {
    return [passwordValid boolValue] ? [UIColor clearColor] : [UIColor yellowColor];
  }]
  subscribeNext:^(UIColor *color) {
    self.passwordTextField.backgroundColor = color;
  }];

看着上面的代码，还行，不过RAC有个更优雅的宏来展现

RAC(self.passwordTextField, backgroundColor) =
  [validPasswordSignal
    map:^id(NSNumber *passwordValid) {
      return [passwordValid boolValue] ? [UIColor clearColor] : [UIColor yellowColor];
    }];

RAC(self.usernameTextField, backgroundColor) =
  [validUsernameSignal
    map:^id(NSNumber *passwordValid) {
     return [passwordValid boolValue] ? [UIColor clearColor] : [UIColor yellowColor];
    }];

通常情况下，登录一般是用户名和密码都匹配后才会在网络好的情况下登录成功。需要 进行信号混合

RACSignal *signUpActiveSignal =
  [RACSignal combineLatest:@[validUsernameSignal, validPasswordSignal]
                    reduce:^id(NSNumber *usernameValid, NSNumber *passwordValid) {
                      return @([usernameValid boolValue] && [passwordValid boolValue]);
                    }];