1.接口文件

/** 为UIRefreshControl绑定指定的task */- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task;复制代码

2.AFRefreshControlNotificationObserver私有类

2.1.属性

/** 保存要绑定task的刷新控件 */@property (readonly, nonatomic, weak) UIRefreshControl *refreshControl;复制代码

2.2.方法

/** 以指定刷新控件初始化的方法 */- (instancetype)initWithActivityRefreshControl:(UIRefreshControl *)refreshControl;/** 为UIRefreshControl绑定指定的task */- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task;复制代码

2.3.实现

接口方法的实现

- (instancetype)initWithActivityRefreshControl:(UIRefreshControl *)refreshControl{    self = [super init];    if (self) {        // 用属性保存传入的参数        _refreshControl = refreshControl;    }    return self;}- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task {    // 创建通知中心对象    NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];    // 先移除掉之前添加通知    [notificationCenter removeObserver:self name:AFNetworkingTaskDidResumeNotification object:nil];    [notificationCenter removeObserver:self name:AFNetworkingTaskDidSuspendNotification object:nil];    [notificationCenter removeObserver:self name:AFNetworkingTaskDidCompleteNotification object:nil];    // 如果传入的task不为nil    if (task) {        // 获取到传入的刷新控件        UIRefreshControl *refreshControl = self.refreshControl;        // 如果task的状态是正在运行中        if (task.state == NSURLSessionTaskStateRunning) {            // 刷新控件开始刷新            [refreshControl beginRefreshing];            // 注册通知监听task的开始、完成和暂停            [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];        // 如果task的状态不是是正在运行中        } else {            // 刷新控件停止刷新            [refreshControl endRefreshing];        }    }}复制代码

通知回调方法的实现

- (void)af_beginRefreshing {    // 在主队列异步调用刷新控件的开始刷新    dispatch_async(dispatch_get_main_queue(), ^{        [self.refreshControl beginRefreshing];    });}- (void)af_endRefreshing {    // 在主队列异步调用刷新控件的停止刷新    dispatch_async(dispatch_get_main_queue(), ^{        [self.refreshControl endRefreshing];    });}复制代码

生命周期方法实现

- (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];}复制代码

3.方法实现

- (AFRefreshControlNotificationObserver *)af_notificationObserver {    // 先通过关联对象获取为分类创建的属性    AFRefreshControlNotificationObserver *notificationObserver = objc_getAssociatedObject(self, @selector(af_notificationObserver));    // 如果属性为空    if (notificationObserver == nil) {        // 创建刷新控件通知观察者对象        notificationObserver = [[AFRefreshControlNotificationObserver alloc] initWithActivityRefreshControl:self];        // 通过关联对象将创建的对象保存到属性中        objc_setAssociatedObject(self, @selector(af_notificationObserver), notificationObserver, OBJC_ASSOCIATION_RETAIN_NONATOMIC);    }    return notificationObserver;}- (void)setRefreshingWithStateOfTask:(NSURLSessionTask *)task {    // 获取到刷新控件通知观察者对象并为之绑定task    [[self af_notificationObserver] setRefreshingWithStateOfTask:task];}复制代码

4.总结

可以看到这个分类的实现基本和UIActivityIndicatorView+AFNetworking分类的实现一模一样。都是依靠分类内部的私有类通过对绑定task相关属性添加通知观察，来控制刷新控件的动作。

源码阅读系列：AFNetworking