AFNetworking是對(duì)NSURLSession的封裝，看AFNetworking之前必須先了解NSURLSession的網(wǎng)絡(luò)請(qǐng)求原理步驟。
1.創(chuàng)建NSURLSessionDataTask
2.配置NSURLSessionDataTask
3.設(shè)置NSURLSessionDataTask的Delegate
4.調(diào)用NSURLSessionDataTask的resume方法開始請(qǐng)求
5.在Delegate的方法里面處理網(wǎng)絡(luò)請(qǐng)求的各個(gè)過程
6.清理NSURLSessionDataTask的配置
雖然代碼很多，但是一點(diǎn)一點(diǎn)慢慢看。example的代碼很規(guī)范，mvc架構(gòu)，從業(yè)務(wù)層開始了解底層。
AppDelegate
在didFinishLaunchingWithOptions函數(shù)中：
1 設(shè)置緩存機(jī)制
NSURLCache *URLCache = [[NSURLCache alloc] initWithMemoryCapacity:4 * 1024 * 1024 diskCapacity:20 * 1024 * 1024 diskPath:nil];
[NSURLCache setSharedURLCache:URLCache];
2 設(shè)置網(wǎng)絡(luò)指示的小菊花
[[AFNetworkActivityIndicatorManager sharedManager] setEnabled:YES];
點(diǎn)擊進(jìn)入AFNetworkActivityIndicatorManager類文件，有注釋,翻譯如下:
AFNetworkActivityIndicatorManager管理狀態(tài)欄中的網(wǎng)絡(luò)活動(dòng)指示器的狀態(tài)。當(dāng)啟用時(shí)，它將偵聽表明task已經(jīng)啟動(dòng)或完成的通知，并相應(yīng)地啟動(dòng)或停止動(dòng)畫指示器。活動(dòng)請(qǐng)求的數(shù)量增加和遞減，就像堆棧或信號(hào)量一樣，活動(dòng)指示符在這個(gè)數(shù)字大于零的情況下也會(huì)被激活。
當(dāng)應(yīng)用程序完成啟動(dòng)時(shí)，應(yīng)該啟用AFNetworkActivityIndicatorManager的共享實(shí)例。在AppDelegate application:didFinishLaunchingWithOptions:你可以使用以下代碼:
[[AFNetworkActivityIndicatorManager sharedManager]setEnabled:YES);
通過為sharedManager設(shè)置enabled為YES，網(wǎng)絡(luò)活動(dòng)指示器將在請(qǐng)求開始和結(jié)束時(shí)自動(dòng)顯示和隱藏。您不需要自己調(diào)用incrementActivityCount或decrementActivityCount。
詳細(xì)內(nèi)容以后閱讀。
3 設(shè)置rootViewController為GlobaltimelineViewController的NavigationController
AFNetworkActivityIndicatorManager
在init方法中self.currentState表示當(dāng)前狀態(tài)初始化是沒有活動(dòng)狀態(tài),是一個(gè)枚舉值，有4個(gè)狀態(tài)值， 2個(gè)定時(shí)器self.activationDelay self.completionDelay。注冊(cè)了3個(gè)通知來接收網(wǎng)絡(luò)狀態(tài)變化。
-
AFNetworkActivityManagerStateNotActive沒有活動(dòng) -
AFNetworkActivityManagerStateDelayingStart開始延時(shí) -
AFNetworkActivityManagerStateActive活動(dòng) -
AFNetworkActivityManagerStateDelayingEnd結(jié)束延時(shí)
當(dāng)網(wǎng)絡(luò)開始請(qǐng)求時(shí)發(fā)送通知網(wǎng)絡(luò)開始活動(dòng)，AFNetworkActivityIndicatorManager類接收到通知后網(wǎng)絡(luò)活動(dòng)數(shù)加1。
- (void)networkRequestDidStart:(NSNotification *)notification {
if ([AFNetworkRequestFromNotification(notification) URL]) {
[self incrementActivityCount];
}
}
- (void)updateCurrentStateForNetworkActivityChange {
if (self.enabled) {
switch (self.currentState) {
case AFNetworkActivityManagerStateNotActive:
if (self.isNetworkActivityOccurring) {
[self setCurrentState:AFNetworkActivityManagerStateDelayingStart];
}
break;
case AFNetworkActivityManagerStateDelayingStart:
//No op. Let the delay timer finish out.
break;
case AFNetworkActivityManagerStateActive:
if (!self.isNetworkActivityOccurring) {
[self setCurrentState:AFNetworkActivityManagerStateDelayingEnd];
}
break;
case AFNetworkActivityManagerStateDelayingEnd:
if (self.isNetworkActivityOccurring) {
[self setCurrentState:AFNetworkActivityManagerStateActive];
}
break;
}
}
}
更新self.curruentState的狀態(tài),一開始默認(rèn)是不活躍狀態(tài)，進(jìn)入
AFNetworkActivityManagerStateNotActive情況,設(shè)置網(wǎng)絡(luò)狀態(tài)DelayingStart。
if (self.isNetworkActivityOccurring) {
[self setCurrentState:AFNetworkActivityManagerStateDelayingStart];
}
點(diǎn)擊進(jìn)入setCurrentState:根據(jù)self.currentState狀態(tài)不同做出不同反應(yīng)，沒有網(wǎng)絡(luò)請(qǐng)求時(shí)取消兩個(gè)定時(shí)器，隱藏小菊花。
- (void)setCurrentState:(AFNetworkActivityManagerState)currentState {
@synchronized(self) {
if (_currentState != currentState) {
[self willChangeValueForKey:@"currentState"];
_currentState = currentState;
switch (currentState) {
case AFNetworkActivityManagerStateNotActive:
[self cancelActivationDelayTimer];
[self cancelCompletionDelayTimer];
[self setNetworkActivityIndicatorVisible:NO];
break;
case AFNetworkActivityManagerStateDelayingStart:
[self startActivationDelayTimer];
break;
case AFNetworkActivityManagerStateActive:
[self cancelCompletionDelayTimer];
[self setNetworkActivityIndicatorVisible:YES];
break;
case AFNetworkActivityManagerStateDelayingEnd:
[self startCompletionDelayTimer];
break;
}
[self didChangeValueForKey:@"currentState"];
}
}
}
DelayingStart狀態(tài)時(shí)添加定時(shí)器，默認(rèn)1秒后執(zhí)行再setCurrentState:方法 currentState改為AFNetworkActivityManagerStateActive，活躍狀態(tài)時(shí)顯示小菊花，幾個(gè)狀態(tài)之間的相互轉(zhuǎn)化很巧妙。
這是設(shè)置小菊花的方法，并且支持自定義
- (void)setNetworkActivityIndicatorVisible:(BOOL)networkActivityIndicatorVisible {
if (_networkActivityIndicatorVisible != networkActivityIndicatorVisible) {
[self willChangeValueForKey:@"networkActivityIndicatorVisible"];
@synchronized(self) {
_networkActivityIndicatorVisible = networkActivityIndicatorVisible;
}
[self didChangeValueForKey:@"networkActivityIndicatorVisible"];
if (self.networkActivityActionBlock) {
self.networkActivityActionBlock(networkActivityIndicatorVisible);
} else {
[[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:networkActivityIndicatorVisible];
}
}
}
復(fù)習(xí)到的知識(shí)點(diǎn)：通知，定時(shí)器，手動(dòng)kvo
GlobalTimelineViewController
GlobalTimelineViewController是繼承uitableViewController
在viewDidLoad函數(shù)中設(shè)置了tableView的上拉下拉刷新控件refreshControl，refreshControl是UITableViewController的屬性，是系統(tǒng)封裝好的刷新控件，添加事件reload，在reload函數(shù)中添加網(wǎng)絡(luò)請(qǐng)求。
UITableViewDataSource代理方法綁定數(shù)據(jù)源設(shè)置cell。數(shù)據(jù)源self.posts是在reload函數(shù)中的block中得到的
NSURLSessionTask *task = [Post globalTimelinePostsWithBlock:^(NSArray *posts, NSError *error) {
if (!error) {
self.posts = posts;
[self.tableView reloadData];
}
}];
[self.refreshControl setRefreshingWithStateOfTask:task];
Model Post類
Post類調(diào)用globalTimelinePostsWithBlock創(chuàng)建一個(gè)網(wǎng)絡(luò)請(qǐng)求任務(wù)，并在返回成功的回調(diào)block中對(duì)進(jìn)入數(shù)據(jù)轉(zhuǎn)模型。example將網(wǎng)絡(luò)請(qǐng)求方法放在model類中，在view controller中Post調(diào)用類方法，block回調(diào)的直接就是模型數(shù)據(jù)了。
+ (NSURLSessionDataTask *)globalTimelinePostsWithBlock:(void (^)(NSArray *posts, NSError *error))block {
return [[AFAppDotNetAPIClient sharedClient] GET:@"stream/0/posts/stream/global" parameters:nil progress:nil success:^(NSURLSessionDataTask * __unused task, id JSON) {
NSArray *postsFromResponse = [JSON valueForKeyPath:@"data"];
NSMutableArray *mutablePosts = [NSMutableArray arrayWithCapacity:[postsFromResponse count]];
for (NSDictionary *attributes in postsFromResponse) {
Post *post = [[Post alloc] initWithAttributes:attributes];
[mutablePosts addObject:post];
}
if (block) {
block([NSArray arrayWithArray:mutablePosts], nil);
}
} failure:^(NSURLSessionDataTask *__unused task, NSError *error) {
if (block) {
block([NSArray array], error);
}
}];
}
在返回成功的回調(diào)中
AFAppDotNetAPIClient是一個(gè)繼承AFHTTPSessionManager的單例類,是對(duì)AFHTTPSessionManager的又一層簡單封裝
+ (instancetype)sharedClient {
static AFAppDotNetAPIClient *_sharedClient = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
_sharedClient = [[AFAppDotNetAPIClient alloc] initWithBaseURL:[NSURL URLWithString:AFAppDotNetAPIBaseURLString]];
_sharedClient.securityPolicy = [AFSecurityPolicy policyWithPinningMode:AFSSLPinningModeNone];
});
return _sharedClient;
}
AFAppDotNetAPIClient發(fā)起一個(gè)GET請(qǐng)求。點(diǎn)擊進(jìn)入其父類AFHTTPSessionManager的GET請(qǐng)求方法：
- (NSURLSessionDataTask *)GET:(NSString *)URLString
parameters:(id)parameters
progress:(void (^)(NSProgress * _Nonnull))downloadProgress
success:(void (^)(NSURLSessionDataTask * _Nonnull, id _Nullable))success
failure:(void (^)(NSURLSessionDataTask * _Nullable, NSError * _Nonnull))failure
{
NSURLSessionDataTask *dataTask = [self dataTaskWithHTTPMethod:@"GET"
URLString:URLString
parameters:parameters
uploadProgress:nil
downloadProgress:downloadProgress
success:success
failure:failure];
[dataTask resume];
return dataTask;
}
UIRefreshControl+AFNetworking
這是一個(gè)UIRefreshControl的category，給UIRefreshControl添加了一個(gè)方法- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task;。點(diǎn)擊進(jìn)入方法實(shí)現(xiàn)。
- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task {
[[self af_notificationObserver] setRefreshingWithStateOfTask:task];
}
因?yàn)閏ategory不能添加實(shí)例變量，作者使用的objc_getAssociatedObject和objc_setAssociatedObject方法來綁定一個(gè)實(shí)例變量af_notificationObserver。
AFRefreshControlNotificationObserver類來實(shí)現(xiàn)setRefreshingWithStateOfTask方法。添加通知前先移除之前的通知，然后再添加3個(gè)通知。
