Swift-【Observable 1】
2021-08-28 本文已影响0人
NJ_墨
let myError = NSError.init(domain: "com.myerror.cn", code: 10010, userInfo: nil)
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catchAndReturn：从错误事件中恢复，返回一个可观察到的序列，该序列发出单个元素，然后终止
func test_catchAndReturn() {
// 从错误事件中恢复，方法是返回一个可观察到的序列，该序列发出单个元素，然后终止
let sequenceThatFails = PublishSubject<String>()
sequenceThatFails
.catchAndReturn("catchAndReturn")
.subscribe{print($0)}
.disposed(by: disposeBag)
sequenceThatFails.onNext("2")
sequenceThatFails.onNext("3")// 正常序列发送成功的
sequenceThatFails.onError(self.myError) //发送失败的序列,一旦订阅到位 返回我们之前设定的错误的预案
sequenceThatFails.onNext("4")
/**
next(2)
next(3)
next(catchAndReturn)
completed
*/
}
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catch：通过切换到提供的恢复可观察序列，从错误事件中恢复
func test_catchError() {
let sequenceThatFails = PublishSubject<String>()
sequenceThatFails
.catchAndReturn("catchAndReturn")
.subscribe{print($0)}
.disposed(by: disposeBag)
// 通过切换到提供的恢复可观察序列，从错误事件中恢复
print("*****catchError*****")
let recoverySequence = PublishSubject<String>()
recoverySequence
.catch {
print("Error:",$0)
return recoverySequence // 获取到了错误序列-我们在中间的闭包操作处理完毕
}
.subscribe{print($0)}
.disposed(by: disposeBag)
sequenceThatFails.onNext("test1")
sequenceThatFails.onNext("test2") // 正常序列发送成功的
sequenceThatFails.onError(myError) // 发送失败的序列
recoverySequence.onNext("rec1")
recoverySequence.onNext("rec2")
sequenceThatFails.onError(self.myError) // 发送失败的序列
recoverySequence.onNext("rec2")
recoverySequence.onNext("rec4")
/**
next(test1)
next(test2)
next(catchAndReturn)
completed
next(rec1)
next(rec2)
next(rec2)
next(rec4)
*/
}
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retry：通过无限地重新订阅可观察序列来恢复重复的错误事件 -
retry(_:): 重试次数达到max未遂计数
func test_retry() {
// retry: 通过无限地重新订阅可观察序列来恢复重复的错误事件
print("*****retry*****")
var count = 1
let sequenceRetryErrors = Observable<String>.create { (observer) -> Disposable in
observer.onNext("1")
observer.onNext("2")
observer.onNext("3")
if count == 1 { // 条件可以作为出口,失败的次数
observer.onError(self.myError)
print("错误序列来了")
count += 1
}
observer.onNext("test1")
observer.onNext("test2")
observer.onNext("test3")
observer.onCompleted()
return Disposables.create()
}
sequenceRetryErrors
.retry() //调用这个retry后，上面的observer闭包会重新执行一次
.subscribe(onNext: {print($0)})
.disposed(by: disposeBag)
/**
*****retry*****
1
2
3
错误序列来了
1
2
3
test1
test2
test3
*/
}
/// retry(_:): 重试次数达到max未遂计数
func test_retry2() {
print("*****retry(_:)*****")
var count = 1
let sequenceThatErrors = Observable<String>.create { observer in
observer.onNext("1")
observer.onNext("2")
observer.onNext("3")
if count < 5 { //
observer.onError(self.myError) //发送错误消息
print("错误序列来了")
count += 1
}
//发送错误后，下面的sender都不会打印了
observer.onNext("sender 1")
observer.onNext("sender 2")
observer.onNext("sender 3")
observer.onCompleted()
return Disposables.create()
}
sequenceThatErrors
.retry(3) //重复地从错误事件中恢复3次
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
/**
*****retry(_:)*****
1
2
3
错误序列来了
1
2
3
错误序列来了
1
2
3
错误序列来了
*/
}
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concat：以顺序方式连接来自一个可观察序列的内部可观察序列的元素，在从下一个序列发出元素之前，等待每个序列成功终止
func test_concat() {
// *** concat:
// 用来控制顺序
let subject1 = BehaviorSubject(value: "1")
let subject2 = BehaviorSubject(value: "11")
let subjectsSubject = BehaviorSubject(value: subject1)
subjectsSubject.asObservable()
.concat()
.subscribe { print($0) }
.disposed(by: disposeBag)
subject1.onNext("2")
subject1.onNext("3")
subjectsSubject.onNext(subject2)
subject1.onNext("4")
subject2.onNext("22")
//subject1.onCompleted() // 必须要等subject1 完成了才能订阅到! 用来控制顺序 网络数据的异步
subject2.onNext("33")
/** 未打开completed
next(1)
next(2)
next(3)
next(4)
*/
/** 打开completed
next(1)
next(2)
next(3)
next(4)
next(22)
next(33)
*/
}
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filter：满足指定条件的可观察序列中发出那些元素
func test_fliter() {
Observable.of(1,2,3,4,5,6,7,8,9,0)
.filter{$0 % 2 == 0}
.subscribe(onNext: {print($0)}) //2 4 6 8 0
.disposed(by: disposeBag)
}
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distinctUntilChanged：抑制可观察序列发出的顺序重复元素
func test_distinctUntilChanged() {
Observable.of("1", "2", "2", "2", "3", "3", "4")
.distinctUntilChanged()
.subscribe(onNext: {print($0)}) //1,2,3,4
.disposed(by: disposeBag)
Observable.of("1", "2", "2", "2", "3", "3", "4")
.distinctUntilChanged()
.toArray()
.subscribe({ value in
print(value) //success(["1", "2", "3", "4"])
})
.disposed(by: disposeBag)
}
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element：在可观察序列发出的所有元素的指定索引处发出元素
func test_elementAt() {
print("*****elementAt*****")
Observable.of("C", "o", "o", "c", "i")
.element(at: 3)
.subscribe(onNext: { print($0) }) //c
.disposed(by: disposeBag)
}
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takeLast：末尾发出指定数量的元素
func test_takeLast() {
Observable.of("1", "2","3", "4","5")
.takeLast(3)//取从末尾开始算起的3个元素
.subscribe(onNext: { print($0) }) //3,4,5
.disposed(by: disposeBag)
}
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take(while:{ $0 < 3 })：指定条件的值为true
func test_takeWhile() {
Observable.of(1, 2, 3, 4, 5, 6)
.take(while:{ $0 < 3 }) //取出满足条件的元素 (1,2)
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
}
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skip：跳过前面两个元素,如textfiled 都会有默认序列产生 -
skip { $0 < 4 }：直接跳过满足条件的元素，相当于过滤作用
func test_skip() {
Observable.of(1,2,3,4,5,6)
.skip(2) //直接跳过前面两个元素，即从3开始
.subscribe(onNext: {print($0)}) //3，4，5，6
.disposed(by: disposeBag)
}
func test_skipWhile() {
Observable.of(1, 2, 3, 4, 5, 6)
.skip { $0 < 4 } //满足小于4的都跳过，即只有4，5，6）
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
}
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take(until: referenceSequence)：从源可观察序列发出元素，直到参考可观察序列发出元素，条件之下不可以输出 -
skip(until: referenceSeq)：直到参考可观察序列发出元素，条件之上才可以输出 - skipUntil 作用和 takeUntil 相反
func test_takeUntil() {
let sourceSequence = PublishSubject<String>()
let referenceSequence = PublishSubject<String>()
sourceSequence
.take(until: referenceSequence)
.subscribe(onNext: {print($0)})
.disposed(by: disposeBag)
sourceSequence.onNext("1")
sourceSequence.onNext("2")
sourceSequence.onNext("3")
//referenceSequence.onNext("0") // 条件一出来,下面就走不了
sourceSequence.onNext("4")
sourceSequence.onNext("5")
sourceSequence.onNext("6")
}
func test_skipUntil() {
// *** skipUntil: 抑制从源可观察序列发出元素，直到参考可观察序列发出元素
let sourceSeq = PublishSubject<String>()
let referenceSeq = PublishSubject<String>()
sourceSeq
.skip(until: referenceSeq)
.subscribe(onNext: { print($0) })
.disposed(by: disposeBag)
//这些不输出
sourceSeq.onNext("1")
sourceSeq.onNext("2")
sourceSeq.onNext("3")
referenceSeq.onNext("0") // 条件一出来,下面就可以走了
sourceSeq.onNext("11")
sourceSeq.onNext("22")
sourceSeq.onNext("33")
}
