variables
Variable 其实就是一个behaviorSubject, 改Variable 仅仅暴漏了一个value 接口，因此variable 不能手动调用终止或失败
只要subscribe 他就会立刻广播他当前的值
func testVariable(){
let variable = Variable(0)
print("before first subscription.....")
let v = variable.asObservable().subscribe(onNext: { (vint) -> Void in
print("first ->\(vint)")
}, onError: { (error) -> Void in
print("error")
}, onCompleted: { () -> Void in
print("completed first .....")
}) { () -> Void in
}
print("before send 1 ")
variable.value = 1;
print("Before second subscription.....")
variable.asObservable().subscribe(onNext: { (value ) -> Void in
print("second->\(value)")
}, onError: { (error) -> Void in
print("error Second")
}, onCompleted: { () -> Void in
print("second completed")
}) { () -> Void in
}
variable.value = 2;
print("end .....")
}
输出如下:
before first subscription.....
first ->0
before send 1
first ->1
Before second subscription.....
second->1// 这个是第一个的值
first ->2
second->2
end .....
completed first .....
second completed
KVO
view.rx_observe(CGRect.self,"frame").subscribeNext{
frame in
....
}
or
view .rx_observeWeakly(CGRect.self, "frame") .subscribeNext { frame in ... }
rx_observe
is more performant because it’s just a simple wrapper around KVO mechanism, but it has more limited usage scenarios
it can be used to observe paths starting from self
or from ancestors in ownership graph (retainSelf = false
)
it can be used to observe paths starting from descendants in ownership graph (retainSelf = true
)
the paths have to consist only of strong
properties, otherwise you are risking crashing the system by not unregistering KVO observer before dealloc.
- rx_observeWeakly
运行效率肯能比rx_observe 慢，因为他需要出路weak reference 的释放。
除了rx_observe 能做的以外，rx_observeWeakly还能
- 可以观察任何拥有关系未知的对象，因为他不会retain 该target
- 可以观察
weak属性
someSuspiciousViewController.rx_observeWeakly(Bool.self, "behavingOk")
Threading
Observable 需要在MainScheduler（UIThread）中发送values
observeOn（MainScheduler.instance）
