AFNetworking 3.0 源码解读（十一）之 UIButton/UIProgressView/UIWebView + AFNetworking

偏执的太偏执、 2023-10-17 14:56 105阅读 0赞

> AFNetworking的源码解读马上就结束了，这一篇应该算是倒数第二篇，下一篇会是对AFNetworking中的技术点进行总结。

#### 前言 ####

[上一篇][Link 1]我们总结了 UIActivityIndicatorView UIRefreshControl UIImageView 这3个控件的分类。那么这一篇就总结下剩余的3个分类：UIButton UIProgressView UIWebView 。

#### UIButton+AFNetworking ####

UIButton跟图片相关的属性大概有两个，`Image`和`BackgroundImage`.所以这个分类就是赋予他们异步加载图片的能力。

其中核心方法为：  
![637318-20160830101357183-1012134374.png][]

![637318-20160830101405433-860115248.png][]

![637318-20160830101413574-1894937106.png][]

示例代码：

static char AFImageDownloadReceiptNormal;
    static char AFImageDownloadReceiptHighlighted;
    static char AFImageDownloadReceiptSelected;
    static char AFImageDownloadReceiptDisabled;
    
    static const char * af_imageDownloadReceiptKeyForState(UIControlState state) {
        switch (state) {
            case UIControlStateHighlighted:
                return &AFImageDownloadReceiptHighlighted;
            case UIControlStateSelected:
                return &AFImageDownloadReceiptSelected;
            case UIControlStateDisabled:
                return &AFImageDownloadReceiptDisabled;
            case UIControlStateNormal:
            default:
                return &AFImageDownloadReceiptNormal;
        }
    }
    
    - (AFImageDownloadReceipt *)af_imageDownloadReceiptForState:(UIControlState)state {
        return (AFImageDownloadReceipt *)objc_getAssociatedObject(self, af_imageDownloadReceiptKeyForState(state));
    }
    
    - (void)af_setImageDownloadReceipt:(AFImageDownloadReceipt *)imageDownloadReceipt
                               forState:(UIControlState)state
    {
        objc_setAssociatedObject(self, af_imageDownloadReceiptKeyForState(state), imageDownloadReceipt, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }

我们分析下上边的代码。我们都知道UIButton有4种状态。这个分类能够支持不同的状态加载不同的图片。同样我们也知道，每一个图片的加载，都需要一个AFImageDownloadReceipt凭证。所以，我们要为UIButton扩展一个根据状态获取凭证的方法，就是：`af_imageDownloadReceiptForState:`。既然有获取凭证的方法，就应该有根据状态设置凭证的方法，那就是：`af_setImageDownloadReceipt: forState:`.

上边的`af_imageDownloadReceiptKeyForState`方法的作用就是为运行时提供一个key，这个key是一个内存地址。[也可使用@Selector][Selector]()。同理，下边的代码扩展了BackgroundImage，原理同上，就不做解释了

示例代码：

static char AFBackgroundImageDownloadReceiptNormal;
    static char AFBackgroundImageDownloadReceiptHighlighted;
    static char AFBackgroundImageDownloadReceiptSelected;
    static char AFBackgroundImageDownloadReceiptDisabled;
    
    static const char * af_backgroundImageDownloadReceiptKeyForState(UIControlState state) {
        switch (state) {
            case UIControlStateHighlighted:
                return &AFBackgroundImageDownloadReceiptHighlighted;
            case UIControlStateSelected:
                return &AFBackgroundImageDownloadReceiptSelected;
            case UIControlStateDisabled:
                return &AFBackgroundImageDownloadReceiptDisabled;
            case UIControlStateNormal:
            default:
                return &AFBackgroundImageDownloadReceiptNormal;
        }
    }
    
    - (AFImageDownloadReceipt *)af_backgroundImageDownloadReceiptForState:(UIControlState)state {
        return (AFImageDownloadReceipt *)objc_getAssociatedObject(self, af_backgroundImageDownloadReceiptKeyForState(state));
    }
    
    - (void)af_setBackgroundImageDownloadReceipt:(AFImageDownloadReceipt *)imageDownloadReceipt
                                         forState:(UIControlState)state
    {
        objc_setAssociatedObject(self, af_backgroundImageDownloadReceiptKeyForState(state), imageDownloadReceipt, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }

示例代码:

// 使用运行时设置sharedImageDownloader
    + (AFImageDownloader *)sharedImageDownloader {
    
    #pragma clang diagnostic push
    #pragma clang diagnostic ignored "-Wgnu"
        return objc_getAssociatedObject(self, @selector(sharedImageDownloader)) ?: [AFImageDownloader defaultInstance];
    #pragma clang diagnostic pop
    }
    // 使用运行时设置setSharedImageDownloader:
    + (void)setSharedImageDownloader:(AFImageDownloader *)imageDownloader {
        objc_setAssociatedObject(self, @selector(sharedImageDownloader), imageDownloader, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }

如果对这个分类的核心方法感兴趣的话，可以参考[上一篇][Link 1]。里边有详细的解释，原理和代码非常非常像，在这里为了节省篇幅就不做多余的说明了。在这个分类中下边图片的那行代码可以注释掉。  
![637318-20160830104605058-347253971.png][]

#### UIProgressView+AFNetworking ####

UIProgressView的这个分类，实现原理就是监听`NSURLSessionUploadTask`或者`NSURLSessionDownloadTask`中的"state" "countOfBytesSent" "countOfBytesReceived" 。然后设置进度就可以了。

示例代码：

- (BOOL)af_uploadProgressAnimated {
        return [(NSNumber *)objc_getAssociatedObject(self, @selector(af_uploadProgressAnimated)) boolValue];
    }
    
    - (void)af_setUploadProgressAnimated:(BOOL)animated {
        objc_setAssociatedObject(self, @selector(af_uploadProgressAnimated), @(animated), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    
    - (BOOL)af_downloadProgressAnimated {
        return [(NSNumber *)objc_getAssociatedObject(self, @selector(af_downloadProgressAnimated)) boolValue];
    }
    
    - (void)af_setDownloadProgressAnimated:(BOOL)animated {
        objc_setAssociatedObject(self, @selector(af_downloadProgressAnimated), @(animated), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }

看到上边的这四个方法，我突然间明白，假如我们需要一个属性记录某一个状态的话，通常我们会写一个属性，但是看上边的代码，是通过扩展了几个方法来达到记录状态的目的。这就说明同样一个结果，可以有不同的实现手段。但我不太明白这两个的区别是什么？

示例代码：

- (void)setProgressWithUploadProgressOfTask:(NSURLSessionUploadTask *)task
                                       animated:(BOOL)animated
    {
        [task addObserver:self forKeyPath:@"state" options:(NSKeyValueObservingOptions)0 context:AFTaskCountOfBytesSentContext];
        [task addObserver:self forKeyPath:@"countOfBytesSent" options:(NSKeyValueObservingOptions)0 context:AFTaskCountOfBytesSentContext];
    
        [self af_setUploadProgressAnimated:animated];
    }
    
    - (void)setProgressWithDownloadProgressOfTask:(NSURLSessionDownloadTask *)task
                                         animated:(BOOL)animated
    {
        [task addObserver:self forKeyPath:@"state" options:(NSKeyValueObservingOptions)0 context:AFTaskCountOfBytesReceivedContext];
        [task addObserver:self forKeyPath:@"countOfBytesReceived" options:(NSKeyValueObservingOptions)0 context:AFTaskCountOfBytesReceivedContext];
    
        [self af_setDownloadProgressAnimated:animated];
    }

示例代码：

- (void)observeValueForKeyPath:(NSString *)keyPath
                          ofObject:(id)object
                            change:(__unused NSDictionary *)change
                           context:(void *)context
    {
        // 判断是不是我们需要的监听对象
        if (context == AFTaskCountOfBytesSentContext || context == AFTaskCountOfBytesReceivedContext) {
            
            // 上传
            if ([keyPath isEqualToString:NSStringFromSelector(@selector(countOfBytesSent))]) {
                if ([object countOfBytesExpectedToSend] > 0) {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        [self setProgress:[object countOfBytesSent] / ([object countOfBytesExpectedToSend] * 1.0f) animated:self.af_uploadProgressAnimated];
                    });
                }
            }
    
            // 下载
            if ([keyPath isEqualToString:NSStringFromSelector(@selector(countOfBytesReceived))]) {
                if ([object countOfBytesExpectedToReceive] > 0) {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        [self setProgress:[object countOfBytesReceived] / ([object countOfBytesExpectedToReceive] * 1.0f) animated:self.af_downloadProgressAnimated];
                    });
                }
            }
    
            // 状态
            if ([keyPath isEqualToString:NSStringFromSelector(@selector(state))]) {
                if ([(NSURLSessionTask *)object state] == NSURLSessionTaskStateCompleted) {
                    @try {
                        
                        // 移除state
                        [object removeObserver:self forKeyPath:NSStringFromSelector(@selector(state))];
    
                        // 移除countOfBytesSent
                        if (context == AFTaskCountOfBytesSentContext) {
                            [object removeObserver:self forKeyPath:NSStringFromSelector(@selector(countOfBytesSent))];
                        }
    
                        // 移除countOfBytesReceived
                        if (context == AFTaskCountOfBytesReceivedContext) {
                            [object removeObserver:self forKeyPath:NSStringFromSelector(@selector(countOfBytesReceived))];
                        }
                    }
                    @catch (NSException * __unused exception) {}
                }
            }
        }
    }

#### UIWebView+AFNetworking ####

UIWebView的这个分类是这几个分类中最让我惊讶的一个。让我真正认识到条条大路通罗马到底是什么意思。有时候人的思想确实会被固有的思维所束缚。这里只是用了UIWebView的loadData:(NSData )data MIMEType:(NSString )MIMEType textEncodingName:(NSString)textEncodingName baseURL:(NSURL )baseURL方法

你会发现使用这个分类配合UIWebView，所有的事情都变得很简单。

示例代码：

@interface UIWebView (_AFNetworking)
    @property (readwrite, nonatomic, strong, setter = af_setURLSessionTask:) NSURLSessionDataTask *af_URLSessionTask;
    @end
    
    @implementation UIWebView (_AFNetworking)
    
    - (NSURLSessionDataTask *)af_URLSessionTask {
        return (NSURLSessionDataTask *)objc_getAssociatedObject(self, @selector(af_URLSessionTask));
    }
    
    - (void)af_setURLSessionTask:(NSURLSessionDataTask *)af_URLSessionTask {
        objc_setAssociatedObject(self, @selector(af_URLSessionTask), af_URLSessionTask, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    
    @end

为UIWebView扩展了一个私有属性af\_URLSessionTask，定义为每一次请求，就会对应一个af\_URLSessionTask。

示例代码：

- (AFHTTPSessionManager  *)sessionManager {
        static AFHTTPSessionManager *_af_defaultHTTPSessionManager = nil;
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            _af_defaultHTTPSessionManager = [[AFHTTPSessionManager alloc] initWithSessionConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
            _af_defaultHTTPSessionManager.requestSerializer = [AFHTTPRequestSerializer serializer];
            _af_defaultHTTPSessionManager.responseSerializer = [AFHTTPResponseSerializer serializer];
        });
    
    #pragma clang diagnostic push
    #pragma clang diagnostic ignored "-Wgnu"
        return objc_getAssociatedObject(self, @selector(sessionManager)) ?: _af_defaultHTTPSessionManager;
    #pragma clang diagnostic pop
    }
    
    - (void)setSessionManager:(AFHTTPSessionManager *)sessionManager {
        objc_setAssociatedObject(self, @selector(sessionManager), sessionManager, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }

为UIWebView扩展的一个sessionManager属性。实现了setter和getter方法。这样在后边直接使用`self.sessionManager`就可以，不用创建了。

示例代码：

- (void)loadRequest:(NSURLRequest *)request
               MIMEType:(NSString *)MIMEType
       textEncodingName:(NSString *)textEncodingName
               progress:(NSProgress * _Nullable __autoreleasing * _Nullable)progress
                success:(NSData * (^)(NSHTTPURLResponse *response, NSData *data))success
                failure:(void (^)(NSError *error))failure
    {
        // 检查参数
        NSParameterAssert(request);
    
        // 如果正处于运行或者暂停装状态，就取消之前的任务task并设置为nil
        if (self.af_URLSessionTask.state == NSURLSessionTaskStateRunning || self.af_URLSessionTask.state == NSURLSessionTaskStateSuspended) {
            [self.af_URLSessionTask cancel];
        }
        self.af_URLSessionTask = nil;
    
        __weak __typeof(self)weakSelf = self;
        NSURLSessionDataTask *dataTask;
        dataTask = [self.sessionManager
                GET:request.URL.absoluteString
                parameters:nil
                progress:nil
                success:^(NSURLSessionDataTask * _Nonnull task, id  _Nonnull responseObject) {
                    __strong __typeof(weakSelf) strongSelf = weakSelf;
                    
                    // 请求成功后，调用success block
                    if (success) {
                        success((NSHTTPURLResponse *)task.response, responseObject);
                    }
                    // 显示数据
                    [strongSelf loadData:responseObject MIMEType:MIMEType textEncodingName:textEncodingName baseURL:[task.currentRequest URL]];
    
                    // 调用webViewDidFinishLoad
                    if ([strongSelf.delegate respondsToSelector:@selector(webViewDidStartLoad:)]) {
                        [strongSelf.delegate webViewDidFinishLoad:strongSelf];
                    }
                }
                failure:^(NSURLSessionDataTask * _Nonnull task, NSError * _Nonnull error) {
                    if (failure) {
                        failure(error);
                    }
                }];
        self.af_URLSessionTask = dataTask;
        
        // 设置progress，这个来自于self.sessionManager
        if (progress != nil) {
            *progress = [self.sessionManager downloadProgressForTask:dataTask];
        }
        
        // 开启任务
        [self.af_URLSessionTask resume];
    
        // 调用webViewDidStartLoad方法
        if ([self.delegate respondsToSelector:@selector(webViewDidStartLoad:)]) {
            [self.delegate webViewDidStartLoad:self];
        }
    }

\--

- (void)loadRequest:(NSURLRequest *)request
               progress:(NSProgress * _Nullable __autoreleasing * _Nullable)progress
                success:(NSString * (^)(NSHTTPURLResponse *response, NSString *HTML))success
                failure:(void (^)(NSError *error))failure
    {
        [self loadRequest:request MIMEType:nil textEncodingName:nil progress:progress success:^NSData *(NSHTTPURLResponse *response, NSData *data) {
            NSStringEncoding stringEncoding = NSUTF8StringEncoding;
            if (response.textEncodingName) {
                CFStringEncoding encoding = CFStringConvertIANACharSetNameToEncoding((CFStringRef)response.textEncodingName);
                if (encoding != kCFStringEncodingInvalidId) {
                    stringEncoding = CFStringConvertEncodingToNSStringEncoding(encoding);
                }
            }
    
            NSString *string = [[NSString alloc] initWithData:data encoding:stringEncoding];
            if (success) {
                string = success(response, string);
            }
    
            return [string dataUsingEncoding:stringEncoding];
        } failure:failure];
    }

#### 总结 ####

就一句话，UIWebView+AFNetworking模拟了UIWebView加载数据的过程。模拟，模拟，模拟。。。

##### 推荐阅读 #####

[AFNetworking 3.0 源码解读（一）之 AFNetworkReachabilityManager][AFNetworking 3.0 _ AFNetworkReachabilityManager]

[AFNetworking 3.0 源码解读（二）之 AFSecurityPolicy][AFNetworking 3.0 _ AFSecurityPolicy]

[AFNetworking 3.0 源码解读（三）之 AFURLRequestSerialization][AFNetworking 3.0 _ AFURLRequestSerialization]

[AFNetworking 3.0 源码解读（四）之 AFURLResponseSerialization][AFNetworking 3.0 _ AFURLResponseSerialization]

[AFNetworking 3.0 源码解读（五）之 AFURLSessionManager][AFNetworking 3.0 _ AFURLSessionManager]

[AFNetworking 3.0 源码解读（六）之 AFHTTPSessionManager][AFNetworking 3.0 _ AFHTTPSessionManager]

[AFNetworking 3.0 源码解读（七）之 AFAutoPurgingImageCache][AFNetworking 3.0 _ AFAutoPurgingImageCache]

[AFNetworking 3.0 源码解读（八）之 AFImageDownloader][AFNetworking 3.0 _ AFImageDownloader]

[AFNetworking 3.0 源码解读（九）之 AFNetworkActivityIndicatorManager][AFNetworking 3.0 _ AFNetworkActivityIndicatorManager]

[AFNetworking 3.0 源码解读（十）之 UIActivityIndicatorView/UIRefreshControl/UIImageView + AFNetworking][Link 1]

[Link 1]: http://www.cnblogs.com/machao/p/5817701.html
[637318-20160830101357183-1012134374.png]: http://images2015.cnblogs.com/blog/637318/201608/637318-20160830101357183-1012134374.png
[637318-20160830101405433-860115248.png]: http://images2015.cnblogs.com/blog/637318/201608/637318-20160830101405433-860115248.png
[637318-20160830101413574-1894937106.png]: http://images2015.cnblogs.com/blog/637318/201608/637318-20160830101413574-1894937106.png
[Selector]: mailto:%E4%B9%9F%E5%8F%AF%E4%BD%BF%E7%94%A8@Selector
[637318-20160830104605058-347253971.png]: http://images2015.cnblogs.com/blog/637318/201608/637318-20160830104605058-347253971.png
[AFNetworking 3.0 _ AFNetworkReachabilityManager]: http://www.cnblogs.com/machao/p/5681645.html
[AFNetworking 3.0 _ AFSecurityPolicy]: http://www.cnblogs.com/machao/p/5704201.html
[AFNetworking 3.0 _ AFURLRequestSerialization]: http://www.cnblogs.com/machao/p/5725874.html
[AFNetworking 3.0 _ AFURLResponseSerialization]: http://www.cnblogs.com/machao/p/5755947.html
[AFNetworking 3.0 _ AFURLSessionManager]: http://www.cnblogs.com/machao/p/5768253.html
[AFNetworking 3.0 _ AFHTTPSessionManager]: http://www.cnblogs.com/machao/p/5790708.html
[AFNetworking 3.0 _ AFAutoPurgingImageCache]: http://www.cnblogs.com/machao/p/5796234.html
[AFNetworking 3.0 _ AFImageDownloader]: http://www.cnblogs.com/machao/p/5803850.html
[AFNetworking 3.0 _ AFNetworkActivityIndicatorManager]: http://www.cnblogs.com/machao/p/5813054.html