源碼閱讀：AFNetworking（十五）——UIRefreshControl+AFNetworking

時間 2019-11-25

標籤源碼閱讀 afnetworking 十五 uirefreshcontrol+afnetworking uirefreshcontrol 简体版

原文原文鏈接

該文章閱讀的AFNetworking的版本爲3.2.0。bash

這個分類能夠爲UIRefreshControl綁定一個task，而後根據task的加載狀態自動開始和結束刷新。異步

1.接口文件

/**
 爲UIRefreshControl綁定指定的task
 */
- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task;
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2.AFRefreshControlNotificationObserver私有類

2.1.屬性

/**
 保存要綁定task的刷新控件
 */
@property (readonly, nonatomic, weak) UIRefreshControl *refreshControl;
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2.2.方法

/**
 以指定刷新控件初始化的方法
 */
- (instancetype)initWithActivityRefreshControl:(UIRefreshControl *)refreshControl;

/**
 爲UIRefreshControl綁定指定的task
 */
- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task;
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2.3.實現

接口方法的實現

- (instancetype)initWithActivityRefreshControl:(UIRefreshControl *)refreshControl
{
    self = [super init];
    if (self) {
        // 用屬性保存傳入的參數
        _refreshControl = refreshControl;
    }
    return self;
}

- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task {
    // 建立通知中心對象
    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];

    // 先移除掉以前添加通知
    [notificationCenter removeObserver:self name:AFNetworkingTaskDidResumeNotification object:nil];
    [notificationCenter removeObserver:self name:AFNetworkingTaskDidSuspendNotification object:nil];
    [notificationCenter removeObserver:self name:AFNetworkingTaskDidCompleteNotification object:nil];

    // 若是傳入的task不爲nil
    if (task) {
        // 獲取到傳入的刷新控件
        UIRefreshControl *refreshControl = self.refreshControl;
        // 若是task的狀態是正在運行中
        if (task.state == NSURLSessionTaskStateRunning) {
            // 刷新控件開始刷新
            [refreshControl beginRefreshing];

            // 註冊通知監聽task的開始、完成和暫停
            [notificationCenter addObserver:self selector:@selector(af_beginRefreshing) name:AFNetworkingTaskDidResumeNotification object:task];
            [notificationCenter addObserver:self selector:@selector(af_endRefreshing) name:AFNetworkingTaskDidCompleteNotification object:task];
            [notificationCenter addObserver:self selector:@selector(af_endRefreshing) name:AFNetworkingTaskDidSuspendNotification object:task];
        // 若是task的狀態不是是正在運行中
        } else {
            // 刷新控件中止刷新
            [refreshControl endRefreshing];
        }
    }
}
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通知回調方法的實現

- (void)af_beginRefreshing {
    // 在主隊列異步調用刷新控件的開始刷新
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.refreshControl beginRefreshing];
    });
}

- (void)af_endRefreshing {
    // 在主隊列異步調用刷新控件的中止刷新
    dispatch_async(dispatch_get_main_queue(), ^{
        [self.refreshControl endRefreshing];
    });
}
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生命週期方法實現

- (void)dealloc {
    // 移除掉添加通知
    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
    
    [notificationCenter removeObserver:self name:AFNetworkingTaskDidCompleteNotification object:nil];
    [notificationCenter removeObserver:self name:AFNetworkingTaskDidResumeNotification object:nil];
    [notificationCenter removeObserver:self name:AFNetworkingTaskDidSuspendNotification object:nil];
}
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3.方法實現

- (AFRefreshControlNotificationObserver *)af_notificationObserver {
    // 先經過關聯對象獲取爲分類建立的屬性
    AFRefreshControlNotificationObserver *notificationObserver = objc_getAssociatedObject(self, @selector(af_notificationObserver));
    // 若是屬性爲空
    if (notificationObserver == nil) {
        // 建立刷新控件通知觀察者對象
        notificationObserver = [[AFRefreshControlNotificationObserver alloc] initWithActivityRefreshControl:self];
        // 經過關聯對象將建立的對象保存到屬性中
        objc_setAssociatedObject(self, @selector(af_notificationObserver), notificationObserver, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    return notificationObserver;
}

- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task {
    // 獲取到刷新控件通知觀察者對象併爲之綁定task
    [[self af_notificationObserver] setRefreshingWithStateOfTask:task];
}
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