使用MVVM模式可以让Model--ViewModel--UI间形成绑定关系，Model数据变化可以通过VM直接更新UI；
在实际的场景，比如一些复杂的情况：
- 多个异步请求，获取到全部回调才更新UI
- 依赖请求，第二个请求依赖于第一个请求结果
- 失败重试，需要自定义重试次数
那MVVM该如何设计呢？
核心业务逻辑还是交给ViewModel处理，暴露接口给外部调用，ViewController/View只做订阅。使用RACSubject(ReactiveObjc)或PublishSubject(RxSwift)来发送数据。
一.Controller/View层的处理
OC
/// 绑定
- (void)bind {
[self.viewModel.dataSubject subscribeNext:^(id _Nullable x) {
NSLog(@"直接获取所有信息信息%@", x);
}];
[self.viewModel.moneySubject subscribeNext:^(id _Nullable x) {
NSLog(@"通过用户信息获取的钱包信息%@", x);
}];
[self.viewModel.orderListSubject subscribeNext:^(id _Nullable x) {
NSLog(@"获取的订单列表%@", x);
}];
}
#pragma mark - 场景1：多个异步请求，全部处理完才回调到同一处去处理
- (void)mutiRequestSingleCompletion {
[self.viewModel multiRequestSingleCompletion];
}
#pragma mark - 场景2：多个异步请求，有序，A请求完再继续B请求（B依赖于A）
- (void)multiRequestDependsOnRequest {
[self.viewModel multiRequestDependsOnRequest];
}
#pragma mark - 场景3：在失败情况下重新请求的
- (void)requestMultiTimesWhenFailed {
[self.viewModel requestMultiTimesWhenFailed];
}
Swift
override func viewDidLoad() {
super.viewDidLoad()
self.bind()
self.baseViewModel.multiRequestSingleCompletion()
self.baseViewModel.multiRequestDependsOnRequest()
self.baseViewModel.requestMultiTimesWhenFailed()
}
// MARK: -绑定
func bind() {
self.baseViewModel.dataSubject.subscribe { val in
print(val.element!);
}.disposed(by: disposeBag)
self.baseViewModel.moneySubject.subscribe { val in
print(val.element!);
}.disposed(by: disposeBag)
self.baseViewModel.orderListSubject.subscribe { val in
print(val.element!);
}.disposed(by: disposeBag)
}
1.多个异步请求，全部处理完才回调到同一处去处理。
假设同时有以下请求：用户信息、钱包信息、订单信息；拿到全部回调后才会更新UI
OC
/// 获取完用户信息、钱包信息、订单信息才会回调一次
- (void)multiRequestSingleCompletion {
// 定义信号
RACSubject *userProfileSubject = [RACSubject subject];
RACSubject *walletSubject = [RACSubject subject];
RACSubject *orderSubject = [RACSubject subject];
// 组合
@weakify(self);
[[RACSignal combineLatest:@[userProfileSubject, walletSubject, orderSubject]]subscribeNext:^(RACTuple * _Nullable x) {
@strongify(self);
NSArray *array = [x allObjects];
[self.dataSubject sendNext:array];
}];
// 发送信号值，没有对subject强引用，直接调用
[self requestUserProfile:^(id _Nonnull info) {
[userProfileSubject sendNext:info];
}];
[self requestUserWallet:^(id _Nonnull info) {
[walletSubject sendNext:info];
}];
[self requestUserOrder:^(id _Nonnull info) {
[orderSubject sendNext:info];
}];
}
Swift
/// 获取完用户信息、钱包信息、订单信息才会回调一次
func multiRequestSingleCompletion() {
// 定义信号
let userProfileSubject = PublishSubject<Any>()
let walletSubject = PublishSubject<Any>()
let orderSubject = PublishSubject<Any>()
// 组合
Observable.combineLatest([userProfileSubject, walletSubject, orderSubject]).subscribe { val in
self.dataSubject.onNext(val.element!)
}.disposed(by: disposeBag)
// 发送
self.requestUserProfile { info in
userProfileSubject.onNext(info)
}
self.requestUserWallet { info in
walletSubject.onNext(info)
}
self.requestUserOrder { info in
orderSubject.onNext(info)
}
}
2.多个异步请求，有序，A请求完再继续B请求（B依赖于A）
需要先获取用户信息，再通过用户信息获取钱包信息
OC
/// 获取完用户信息，再通过用户信息获取钱包
- (void)multiRequestDependsOnRequest {
RACSignal *signal = [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber> _Nonnull subscriber) {
[subscriber sendNext:@{@"name":@"Tom"}];
[subscriber sendCompleted];
return nil;
}];
@weakify(self);
signal = [signal flattenMap:^__kindof RACSignal * _Nullable(id _Nullable value) {
NSLog(@"用户%@", value);
return [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber> _Nonnull subscriber) {
@strongify(self);
[self requestUserWallet:^(id _Nonnull info) {
[subscriber sendNext:@{@"money":@"100"}];
[subscriber sendCompleted];
}];
return nil;
}];
}];
[signal subscribeNext:^(id _Nullable x) {
@strongify(self);
[self.moneySubject sendNext:x];
}];
}
Swift
/// 获取完用户信息，再通过用户信息获取钱包
func multiRequestDependsOnRequest() {
var observable = Observable<Any>.create { observer in
observer.onNext(["name":"Tom"])
return Disposables.create()
}
observable = observable.flatMap { val in
return Observable<Any>.create { observer in
self.requestUserWallet { val in
observer.onNext(["money":"100"])
}
return Disposables.create()
}
}
observable.subscribe { val in
self.moneySubject.onNext(val.element!)
}.disposed(by: disposeBag)
}
3.在失败情况下重新请求
最多允许请求失败的次数为retryTimes，超过retryTimes则停止任务，发送错误原因
OC
/// 请求失败后重试
- (void)requestMultiTimesWhenFailed {
@weakify(self);
__block NSInteger failedTimes = 0;
RACSignal *signal = [RACSignal createSignal:^RACDisposable * _Nullable(id<RACSubscriber> _Nonnull subscriber) {
@strongify(self);
[self requestOrderList:^(BOOL status, id _Nonnull info) {
if (!status) {
failedTimes ++;
if (failedTimes <= self.retryTimes) {
NSLog(@"请求失败次数%ld", failedTimes);
[subscriber sendError:nil];
} else {
NSLog(@"请求失败次数%ld，不再自动请求", failedTimes);
}
} else {
[subscriber sendNext:info];
}
}];
return nil;
}];
RACSignal *retrySignal = [signal retry];
[retrySignal subscribeNext:^(id _Nullable x) {
@strongify(self);
[self.orderListSubject sendNext:x];
}];
}
Swift
/// 请求失败后重试，获取订单信息
func requestMultiTimesWhenFailed() {
Observable<Any>.create { observer in
self.requestOrderList { status, val in
if status == true {
observer.onNext(val)
} else {
self.curFailedTimes += 1
if self.retrytimes < self.curFailedTimes {
} else {
print("失败\(self.curFailedTimes)")
observer.onError(NSError(domain: "网络异常", code: 502, userInfo: nil))
}
}
}
return Disposables.create()
}.retry(self.retrytimes).subscribe { val in
self.orderListSubject.onNext(val)
} onError: { error in
print(error.localizedDescription);
}.disposed(by: disposeBag)
}
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