通过上一篇探索RXSwift核心逻辑（一）的介绍，相信小伙伴们对于，RxSwift这个函数响应式编程框架有了一个较为深刻的认识，今天我们来介绍下RxSwift中各种Observable 可观察序列的创建，希望能够带给各位小伙伴一些帮助。
Observable创建
empty
let emtyOb = Observable<Int>.empty()
_ = emtyOb.subscribe(onNext: { (number) in
print("订阅:",number)
}, onError: { (error) in
print("error:",error)
}, onCompleted: {
print("完成回调")
}) {
print("释放回调")
}
//打印 完成回调 释放回调
- 首先来一个空的序列 - 本来序列事件是
Int类型的,这里调用emty函数 没有序列,只能complete
just
let array = ["AAA","BBB"]
Observable<[String]>.just(array)
.subscribe { (event) in
print(event)
}.disposed(by: disposeBag)
_ = Observable<[String]>.just(array).subscribe(onNext: { (number) in
print("订阅:",number)
}, onError: { (error) in
print("error:",error)
}, onCompleted: {
print("完成回调")
}) {
print("释放回调")
}
//打印
//next(["AAA", "BBB"])
//completed
//订阅: ["AAA", "BBB"]
//完成回调
//释放回调
-
just单个信号序列创建,订阅一次数据后立刻自动调用completed,销毁内存
Observable<String>.of("AAA","BBB")
.subscribe { (event) in
print(event)
}.disposed(by: disposeBag)
let ob = Observable<String>.of("AAA","BBB")
_ = ob.subscribe(onNext: { (element) in
print(element)
}, onCompleted: {
print("完成回调")
}, onDisposed: {
print("释放回调")
})
********of********
//next(AAA)
//next(BBB)
//completed
//订阅（AAA)
//订阅（BBB)
//完成回调
//释放回调
-
of针对多个元素的序列处理
Observable<[String]>.from(optional: ["AAA","BBB"])
.subscribe { (event) in
print(event)
}.disposed(by: disposeBag)
*from从集合中获取序列: 数组,集合,set 获取序列 - 有可选项处理 - 更安全
var isOdd = true
_ = Observable<Int>.deferred { () -> Observable<Int> in
// 这里设计我们的序列
isOdd = !isOdd
if isOdd {
return Observable.of(1,3,5,7,9)
}
return Observable.of(0,2,4,6,8)
}
.subscribe { (event) in
print(event)
}
//next(0)
//next(2)
//next(4)
//next(6)
//next(8)
//completed
- 使用
deferred()方法延迟Observable序列的初始化，通过传入的block来实现Observable序列的初始化并且返回。
Observable.range(start: 2, count: 5)
.subscribe { (event) in
print(event)
}.disposed(by: disposeBag)
//打印
//next(2)
//next(3)
//next(4)
//next(5)
//next(6)
//completed
-
range生成指定范围内的可观察整数序列
Observable.generate(initialState: 0,// 初始值
condition: { $0 < 10}, // 条件1
iterate: { $0 + 2 }) // 条件2 +2
.subscribe { (event) in
print(event)
}.disposed(by: disposeBag)
//打印
//next(0)
//next(2)
//next(4)
//next(6)
//next(8)
//completed
let arr = ["AAA_1","AAA_2","AAA_3","AAA_4","AAA_5","AAA_6","AAA_7","AAA_8","AAA_9","AAA_10"]
Observable.generate(initialState: 0,// 初始值
condition: { $0 < arr.count}, // 条件1
iterate: { $0 + 1 }) // 条件2 +2
.subscribe(onNext: {
print("遍历arr:",arr[$0])
})
.disposed(by: disposeBag)
-
generate该方法创建一个只有当提供的所有的判断条件都为 true 的时候，才会给出动作的 Observable 序列。初始值给定 然后判断条件1 再判断条件2 会一直递归下去,直到条件1或者条件2不满足，类似for循环遍历数组
// 第一次参数:第一次响应距离现在的时间 也就是延迟几秒处罚
// 第二个参数:时间间隔
// 第三个参数:线程
let timer = Observable<Int>.timer(1, period: 1, scheduler: MainScheduler.instance)
.takeUntil(.exclusive, predicate: { (num) -> Bool in
if (num == self.countDownSeconds+1) {
return true
}else{
return false
}
})
.map{self.countDownSeconds - $0}
.filter { $0 >= 0 }
.asObservable()
let second = btn.rx.tap.flatMapLatest { _ -> Observable<Int> in
return timer
}
second.map { $0 == 0 ? "发送验证码":"再次发送(\($0)s)"}.bind(to: self.btn.rx.title()).disposed(by: disposeBag)
second.map{ $0 == 0 ? true : false }.bind(to: self.btn.rx.isEnabled).disposed(by: disposeBag)
timer.subscribe { (event) in
print(event)
}.disposed(by: disposeBag)
next(10)
next(9)
next(8)
next(7)
next(6)
next(5)
next(4)
next(3)
next(2)
next(1)
next(0)
completed
- 上图为利用
timer实现的登录按钮发送验证码功能，利用takeUntil ()函数为闭包返回true时发送完成
以上为RxSwift-Observable创建中的一些api的介绍，未完待续。
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