在 NSURLProtocol 中使用 NSURLSession

Question

我正在尝试使用 NSURLSession 为 http:// 和 https:// 连接创建一个透明的 NSURL 协议。但是目前，即使完成处理程序正在运行，应用程序 (UIWebView) 的 URL 请求返回空白。有人有什么想法吗？代码如下：

#import "MyURLProtocol.h"

// AppDelegate
#import "AppDelegate.h"

static NSString * const MyURLProtocolHandledKey = @"MyURLProtocolHandledKey";

@interface MyURLProtocol () <NSURLConnectionDelegate,NSURLSessionDelegate>

@property (nonatomic, strong) NSURLConnection *connection;
@property (nonatomic, strong) NSMutableData *mutableData;
@property (nonatomic, strong) NSURLResponse *response;

@end

@implementation MyURLProtocol

+(BOOL)canInitWithRequest:(NSURLRequest*)request
{
    if ([NSURLProtocol propertyForKey:MyURLProtocolHandledKey inRequest:request])
        return NO;
    NSString *scheme = request.URL.scheme.lowercaseString;
    return [scheme isEqualToString:@"http"] || [scheme isEqualToString:@"https"];
}

+ (NSURLRequest *) canonicalRequestForRequest:(NSURLRequest *)request {
    return request;
}

-(void)startLoading
{      
    NSMutableURLRequest *newRequest = [self.request mutableCopy];
    [NSURLProtocol setProperty:@YES forKey:@"MyURLProtocolHandledKey" inRequest:newRequest];

    NSURLRequest *request = newRequest;

    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request
                                            completionHandler:
                                  ^(NSData *data, NSURLResponse *response, NSError *error) {
                                      if (error != nil) {
                                          NSLog(@"There was an error");
                                      }
                                      NSLog(@"Completiio handler ran");
                                      self.mutableData = [NSMutableData dataWithData:data];
                                      self.response = response;
                                  }];

    [task resume];
}

- (void) stopLoading {

    [self.connection cancel];
    self.mutableData = nil;
}

// Delegate stuff

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    [self.client URLProtocol:self didLoadData:data];
}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
    [self.client URLProtocolDidFinishLoading:self];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    [self.client URLProtocol:self didFailWithError:error];
}

@end

Answer 1

您的代码使用 NSURLConnection 委托将数据传回给调用者，例如connectionDidFinishLoading:.

解决这个问题：

将它们替换为 NSURLSession 委托方法。
创建并保留一个自定义会话，其委托是您的协议 class 实例；共享会话没有委托，因此它不会调用您的 class 的委托方法。
删除回调块，以便正确调用请求完成的委托方法。

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