NSURLProtocol subclass that allows downloads to be intercepted.

BLCURLProtocol.m

//
//  BLCURLProtocol.m
//  URLProtocol
//
//  Created by Matthew Robinson on 17/09/13.
//  Copyright (c) 2013 Blended Cocoa. All rights reserved.
//

#import "BLCURLProtocol.h"

@interface BLCURLProtocol ()

@property (strong,nonatomic) NSURLConnection *connection;

@end

@implementation BLCURLProtocol

+ (BOOL)canInitWithRequest:(NSURLRequest *)request {
    
    // If the request has the property set then we have already dealt with this request.

    if ([NSURLProtocol propertyForKey:NSStringFromClass([self class]) inRequest:request]) {
        return NO;
    }
    
    return YES;
}


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

- (void)startLoading {
    NSLog(@"startLoading");
    
    // Copy the request and a property so we don't deal with this request when it comes through again.

    NSMutableURLRequest *newRequest = [self.request mutableCopy];
    
    [NSURLProtocol setProperty:@YES forKey:NSStringFromClass([self class]) inRequest:newRequest];
    

    // Create a new NSURLConnection and we will proxy the new request to the original request.
    self.connection = [NSURLConnection connectionWithRequest:newRequest delegate:self];
}

- (void)stopLoading {
    [self.connection cancel];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"%@", response);
    
    [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageAllowed];
}

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

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


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

@end