RAC基本用法¶
监听方法¶
rac_signalForSelector
RACView *v = [[RACView alloc]initWithFrame:CGRectMake(100, 300, 150, 80)];
[self.view addSubview:v];
[[v rac_signalForSelector:@selector(testRACView:par:)] subscribeNext:^(RACTuple * _Nullable x) {
NSLog(@"我检测到了视图方法的调用");
}];
点击查看方法调用
- (RACSignal *)rac_signalForSelector:(SEL)selector {
NSCParameterAssert(selector != NULL);
return NSObjectRACSignalForSelector(self, selector, NULL);
}
//返回值是一个RACSignal
static RACSignal *NSObjectRACSignalForSelector(NSObject *self, SEL selector, Protocol *protocol) {
SEL aliasSelector = RACAliasForSelector(selector);
@synchronized (self) {
//创建的是RACSubject
RACSubject *subject = objc_getAssociatedObject(self, aliasSelector);
if (subject != nil) return subject;
Class class = RACSwizzleClass(self);
NSCAssert(class != nil, @"Could not swizzle class of %@", self);
subject = [[RACSubject subject] setNameWithFormat:@"%@ -rac_signalForSelector: %s", RACDescription(self), sel_getName(selector)];
objc_setAssociatedObject(self, aliasSelector, subject, OBJC_ASSOCIATION_RETAIN);
[self.rac_deallocDisposable addDisposable:[RACDisposable disposableWithBlock:^{
[subject sendCompleted];
}]];
Method targetMethod = class_getInstanceMethod(class, selector);
if (targetMethod == NULL) {
const char *typeEncoding;
if (protocol == NULL) {
typeEncoding = RACSignatureForUndefinedSelector(selector);
} else {
// Look for the selector as an optional instance method.
struct objc_method_description methodDescription = protocol_getMethodDescription(protocol, selector, NO, YES);
if (methodDescription.name == NULL) {
// Then fall back to looking for a required instance
// method.
methodDescription = protocol_getMethodDescription(protocol, selector, YES, YES);
NSCAssert(methodDescription.name != NULL, @"Selector %@ does not exist in <%s>", NSStringFromSelector(selector), protocol_getName(protocol));
}
typeEncoding = methodDescription.types;
}
RACCheckTypeEncoding(typeEncoding);
// Define the selector to call -forwardInvocation:.
if (!class_addMethod(class, selector, _objc_msgForward, typeEncoding)) {
NSDictionary *userInfo = @{
NSLocalizedDescriptionKey: [NSString stringWithFormat:NSLocalizedString(@"A race condition occurred implementing %@ on class %@", nil), NSStringFromSelector(selector), class],
NSLocalizedRecoverySuggestionErrorKey: NSLocalizedString(@"Invoke -rac_signalForSelector: again to override the implementation.", nil)
};
return [RACSignal error:[NSError errorWithDomain:RACSelectorSignalErrorDomain code:RACSelectorSignalErrorMethodSwizzlingRace userInfo:userInfo]];
}
} else if (method_getImplementation(targetMethod) != _objc_msgForward) {
// Make a method alias for the existing method implementation.
const char *typeEncoding = method_getTypeEncoding(targetMethod);
RACCheckTypeEncoding(typeEncoding);
BOOL addedAlias __attribute__((unused)) = class_addMethod(class, aliasSelector, method_getImplementation(targetMethod), typeEncoding);
NSCAssert(addedAlias, @"Original implementation for %@ is already copied to %@ on %@", NSStringFromSelector(selector), NSStringFromSelector(aliasSelector), class);
// Redefine the selector to call -forwardInvocation:.
class_replaceMethod(class, selector, _objc_msgForward, method_getTypeEncoding(targetMethod));
}
return subject;
}
}
从上面可以看出返回值是信号，既然是信号那就可以订阅
内部创建的是subject，那就可以发送信号，订阅信号
所以我们在调用rac_signalForSelector这个方法可以直接订阅，内部又是一个subject，所以他会发送信号给到我们
监听属性¶
通常我们要使用KVO需要addObserver并且还要在observeValueForKeyPath...这个方法中去监听，
如果一个界面监听多个还需要判断，还必须记得释放掉。
但是这些东西在RAC中就做了一层包装，现在我们如果想监听对象的某个属性，就可以写如下代码就可以完成，
并且针对某个属性都会产生不同的信号，我们只需要监听所产生的信号在进行处理就可以了
//监听属性
// 方法一
[v rac_observeKeyPath:@"frame" options:NSKeyValueObservingOptionNew observer:nil block:^(id value, NSDictionary *change, BOOL causedByDealloc, BOOL affectedOnlyLastComponent) {
NSLog(@"1 - %@",value);
}];
// 方法二
[[v rac_valuesForKeyPath:@"frame" observer:nil] subscribeNext:^(id _Nullable x) {
NSLog(@"2 - %@",x);
}];
// 方法三
[RACObserve(v, frame) subscribeNext:^(id _Nullable x) {
NSLog(@"3 - %@",x);
}];
v.frame = CGRectMake(100, 400, 150, 100);
注意：写法二、写法三需要在程序运行的时候就会监听到，通过log就可以看出区别。
UISwitch¶
[[[cell.pushSwitch rac_newOnChannel] takeUntil:cell.rac_prepareForReuseSignal] subscribeNext:^(NSNumber *isOn) {
//方法
}];
监听UIControl事件¶
[[button rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(__kindof UIControl * _Nullable x) {
NSLog(@"点击按钮了");
}];
UIControl分类内部实现¶
- (RACSignal *)rac_signalForControlEvents:(UIControlEvents)controlEvents {
@weakify(self);
return [[RACSignal
createSignal:^(id<RACSubscriber> subscriber) {
@strongify(self);
/// 关键代码
/// self：btn本身，因为是btn调用的方法
/// target：subscriber订阅者
/// action：传入的block事件。sendNext: 方法会触发订阅者的subscribeNext
/// 按钮的点击方法会通过`subscriber`去调用`sendNext方法`,我们之前有提到过，`RACSignal`，所以这个时候我们订阅他就可以拿到`sendNext`的值。
[self addTarget:subscriber action:@selector(sendNext:) forControlEvents:controlEvents];
RACDisposable *disposable = [RACDisposable disposableWithBlock:^{
[subscriber sendCompleted];
}];
[self.rac_deallocDisposable addDisposable:disposable];
return [RACDisposable disposableWithBlock:^{
@strongify(self);
[self.rac_deallocDisposable removeDisposable:disposable];
[self removeTarget:subscriber action:@selector(sendNext:) forControlEvents:controlEvents];
}];
}]
setNameWithFormat:@"%@ -rac_signalForControlEvents: %lx", RACDescription(self), (unsigned long)controlEvents];
}
手势¶
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];
[textLab addGestureRecognizer:tap];
[[tap rac_gestureSignal] subscribeNext:^(id x) {
NSLog(@"点击Lab");
}];
通知¶
[[[NSNotificationCenter defaultCenter] rac_addObserverForName:UIKeyboardDidShowNotification object:nil] subscribeNext:^(NSNotification * _Nullable x) {
NSLog(@"%@",x);
}];
内部是怎么样处理：
- (RACSignal *)rac_addObserverForName:(NSString *)notificationName object:(id)object {
@unsafeify(object);
return [[RACSignal createSignal:^(id<RACSubscriber> subscriber) {
@strongify(object);
id observer = [self addObserverForName:notificationName object:object queue:nil usingBlock:^(NSNotification *note) {
[subscriber sendNext:note];
}];
return [RACDisposable disposableWithBlock:^{
[self removeObserver:observer];
}];
}] setNameWithFormat:@"-rac_addObserverForName: %@ object: <%@: %p>", notificationName, [object class], object];
}
没错又是RACSignal，这个里面的代码很简单，就是调用系统提供的方法，在block中使用订阅者发布信息，在RACDisposable中把observer移除。
监听textfield输入¶
[textField.rac_textSignal subscribeNext:^(NSString * _Nullable x) {
NSLog(@"%@",x);
label.text = x;
}];
textField的文字改变，同时修改label的文字。
RAC(label,text) = textField.rac_textSignal;
其中RAC是一个宏，宏的用法：
RAC(对象，对象的属性) = (一个信号); 比如：RAC(btn,enable) = (RACSignal) 按钮的enable等于一个信号
代替代理¶
通常需要定义代理，实现代理协议方法，并且还要注意循环引用等问题存在，RAC也可以做到代替代理。
创建一个view，内部添加一个button。我们要做的就是监听button按下事件。
1、在处理完成UI之后，创建一个GreenView，并导入头文件#import "ReactiveObjC.h"
2、创建一个RACSubject并且命名为btnClickSignal，这里大家需要注意是命名尽量规范，否则以后维护起来你会很痛苦。然后这里为什么会用RACSubject，因为RACSubject可以自己控制发送数据时间。
目前为止代码应该类似于这样子：
#import <UIKit/UIKit.h>
#import "ReactiveObjC.h"
@interface GreenView : UIView
@property (nonatomic,strong) RACSubject *btnClickSignal;
@end
进入.m文件，完成下面代码
#import "GreenView.h"
@implementation GreenView
- (RACSubject *)btnClickSignal{
if (!_btnClickSignal) {
_btnClickSignal = [RACSubject subject];
}
return _btnClickSignal;
}
- (IBAction)btnClick:(id)sender{
[_btnClickSignal sendNext:@"我可以代替代理哦"];
}
@end
上面代码中完成了两个功能：懒加载RACSubject，以及在按钮点击时候发布数据
然后回到ViewController中
- (void)replaceDelegate{
[_greenView.btnClickSignal subscribeNext:^(id _Nullable x) {
NSLog(@"%@",x);
}];
}
这样处理事件更简单和内聚，管理起来也方便。