iOS 开发之 ReactiveCocoa(进阶)

Map : 映射

UITextField *textField =[[UITextField alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];

textField.backgroundColor =[UIColor redColor];

[self.view addSubview:textField];

[[textField.rac_textSignal map:^id(NSString * value) {

return @(value.length);

}] subscribeNext:^(NSNumber * x) {

NSLog(@"%@",x);

}];

输入Ricky:

结果:

filter: 过滤

//只有当text.length>3的时候才会订阅改消息

[[textField.rac_textSignal filter:^BOOL(NSString * text) {

return text.length>3;

}] subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

同样输入Ricky结果就是:

delay:延时

//延时2秒发送消息

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky"];

[subscriber sendCompleted];

return nil;

}] delay:2];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

startWith:在发送消息之前,先发送一个消息

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky"];

[subscriber sendCompleted];

return nil;

}] startWith:@"RAC"];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

timeout :超时

//设置超时时间为2秒,当超过2秒还没有发送消息的时候,就不会发送了

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[[RACScheduler mainThreadScheduler] afterDelay:3 schedule:^{

[subscriber sendNext:@"Ricky"];

[subscriber sendCompleted];

}];

return nil;

}] timeout:2 onScheduler:[RACScheduler mainThreadScheduler]];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

take :发送多个消息的时候,取最前面的几条

 

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky1"];

[subscriber sendNext:@"Ricky2"];

[subscriber sendNext:@"Ricky3"];

[subscriber sendNext:@"Ricky4"];

[subscriber sendCompleted];

return nil;

}] take:2];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

takelast :发送多个消息的时候,取最后面的几条

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky1"];

[subscriber sendNext:@"Ricky2"];

[subscriber sendNext:@"Ricky3"];

[subscriber sendNext:@"Ricky4"];

[subscriber sendCompleted];

return nil;

}] takeLast:3];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

takeUntil: RACSignal (发送在takeUntil后面的信号完成前的消息)

// RAC这个消息是2秒后完成,所以Ricky1 Ricky2这两个消息是可以发送到 而3秒后的Ricky3 Ricky4就不会发送.

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky1"];

[subscriber sendNext:@"Ricky2"];

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

[subscriber sendNext:@"Ricky3"];

[subscriber sendNext:@"Ricky4"];

[subscriber sendCompleted];

});

[subscriber sendCompleted];

return nil;

}] takeUntil:[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

[subscriber sendNext:@"RAC"];

[subscriber sendCompleted];

});

return nil;

}]];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

takeWhileBlock :当takeWhileBlock返回YES的时候发送消息

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky1"];

[subscriber sendNext:@"Ricky2"];

[subscriber sendNext:@"Ricky3"];

[subscriber sendNext:@"Ricky4"];

[subscriber sendCompleted];

return nil;

}] takeWhileBlock:^BOOL(id x) {

return YES;

}];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

skip: 跳过

//跳过前2次

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Ricky1"];

[subscriber sendNext:@"Ricky2"];

[subscriber sendNext:@"Ricky3"];

[subscriber sendNext:@"Ricky4"];

[subscriber sendCompleted];

return nil;

}] skip:2];

[signal subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

skipWhileBlcok 和 skipUntilBlcok

• skipWhileBlcok:当Block返回YES的时候跳过,返回No的时候发送.

• skipUntilBlcok: skipUntilBlcok和skipWhileBlcok相反,当Block返回NO的时候跳

• 过,返回YES的时候发送.

结合及时搜索优化

当我们在做及时搜索的时候,例如在UITextField中输入搜索内容,每当我们输入一个字符的时候当会请求服务器,无形中给服务器带来了很大的压力

UITextField *textField =[[UITextField alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];

textField.backgroundColor =[UIColor redColor];

[self.view addSubview:textField];

[textField.rac_textSignal subscribeNext:^(NSString * text) {

NSLog(@"request--- %@",text);

}];

• 优化请求时间间隔:throttle(节流)

throttle:设置一个间隔时间,当两次信号之间的时间差下于这个时间就不会发送请求

[[textField.rac_textSignal throttle:0.3] subscribeNext:^(NSString * text) {

NSLog(@"request--- %@",text);

}];

• distinctUntilChanged: 优化请求字符一样的时候(当后一个请求和前一个请求一样的时候,就可以不用请求)

[[[textField.rac_textSignal throttle:0.3]distinctUntilChanged]

subscribeNext:^(NSString * text) {

NSLog(@"request--- %@",text);

}];

• ignore :忽略某些 例如上面的空字符

[[[[textField.rac_textSignal throttle:0.3]distinctUntilChanged] ignore:@"" ]

subscribeNext:^(NSString * text) {

NSLog(@"request--- %@",text);

}];

• switchToLatest :当你请求数据的时候,网络会有延迟,数据还没有返回回来,这时候你发送了新的请求,则我们取消前一次的请求,只发送最新的请求.

[[[[[[textField.rac_textSignal throttle:0.3]distinctUntilChanged] ignore:@"" ] map:^id(id value) {

return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

[subscriber sendNext:@"Request --- ricky"];

return nil;

}];

}] switchToLatest]

subscribeNext:^(NSString * text) {

NSLog(@"request--- %@",text);

}];

多个信号处理

 

RACSignal *singalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

[subscriber sendNext:@"singalA"];

[subscriber sendCompleted];

});

return nil;

}];

RACSignal *singalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{

[subscriber sendNext:@"singalB"];

[subscriber sendCompleted];

});

return nil;

}];

merge: 同时订阅2个信号

[[singalA merge:singalB] subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

singalA延迟2秒,singalB延迟5秒,她们相差了3秒.说明他们是同时发送的

concat

singalA完成后 才会订阅singalB 有点像串行队列 A失败了 B就不会被订阅

[[singalA concat:singalB] subscribeNext:^(id x) {

NSLog(@"%@",x);

}];

singalA延迟2秒,singalB延迟5秒,她们相差了5秒.说明A发送完,B才发送的.

zipWith和combineLatest:每个信号都至少要发送一次才可以被订阅.

 

[[singalA zipWith:singalB] subscribeNext:^(RACTuple * tuple) {

NSLog(@"%@",tuple);

}];

[[RACSignal combineLatest:@[singalA,singalB]] subscribeNext:^(RACTuple * tuple) {

NSLog(@"%@",tuple);

}];

RAC中的宏(结合例子)

• UIButton中没有setbackgroundColor forstatus这个方法,使用RAC很简单实现

UIButton *button =[UIButton buttonWithType:UIButtonTypeCustom];

button.frame = CGRectMake(100, 100, 100, 100);

button.backgroundColor = [UIColor yellowColor];

[self.view addSubview:button];

RAC(button,backgroundColor) = [RACObserve(button, selected) map:^id(NSNumber * selected) {

return [selected boolValue]?[UIColor yellowColor]:[UIColor redColor];

}];

[[button rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(UIButton * x) {

x.selected = !x.selected;

}];

• RAC快速实现秒表

UILabel *lab =[[UILabel alloc]initWithFrame:CGRectMake(100, 100, 200, 50)];

lab.backgroundColor =[UIColor cyanColor];

[self.view addSubview:lab];

RAC(lab,text) = [[RACSignal interval:1 onScheduler:[RACScheduler mainThreadScheduler]] map:^id(NSData * value) {

return value.description;

}];