NSURLProtocolを使ってフィルタリングする

MyURLProtocol.m

//
//  MyURLProtocol.m
//
//  Created by kitagawa on 2014/08/21.
//  Copyright (c) 2014年 kitagawa. All rights reserved.
//

#import "MyURLProtocol.h"

static NSString *kCustomHeaderKey = @"API-Key";
static NSString *kCustomHeaderValue = @"OK, this is API-Key";
static NSString *kLoadURLString = @"http://localhost:8888/html/test.html";
static NSString *kSamplePostURLString = @"http://httpbin.org/post";
static NSString *kSampleGetURLString = @"http://httpbin.org/get";
static NSString *kURLSchemeHTTP = @"http";
static NSString *kURLSchemeHTTPS = @"https";


@interface MyURLProtocol () <NSURLConnectionDataDelegate, NSURLConnectionDelegate>

@property (nonatomic, strong) NSURLRequest *request;
@property (nonatomic, strong) NSURLConnection *connection;

@end

@implementation MyURLProtocol

+ (void)load
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [NSURLProtocol registerClass:[self class]];
    });
}

+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
    NSLog(@"url: %@", request.URL);
    NSLog(@"request headers: %@", request.allHTTPHeaderFields);
    NSString *scheme = request.URL.scheme;
    
    if ([request valueForHTTPHeaderField:kCustomHeaderKey]) {
        return NO;
    }
    
    if (([scheme compare:kURLSchemeHTTP] == NSOrderedSame
        || [scheme compare:kURLSchemeHTTPS] == NSOrderedSame)
        && [[self targetURL] containsObject:[request.URL absoluteString]]) {
        return YES;
    }
    return NO;
}

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

- (id)initWithRequest:(NSURLRequest *)request cachedResponse:(NSCachedURLResponse *)cachedResponse client:(id<NSURLProtocolClient>)client
{
    self = [super initWithRequest:request cachedResponse:cachedResponse client:client];
    if (self) {
        NSMutableURLRequest *mutableRequest = [request mutableCopy];
        [mutableRequest setValue:kCustomHeaderValue forHTTPHeaderField:kCustomHeaderKey];
        self.request = (NSURLRequest *)mutableRequest;
    }
    return self;
}

- (void)startLoading
{
    NSLog(@">>>startLoading");
    self.connection = [[NSURLConnection alloc]
                       initWithRequest:[[self class] canonicalRequestForRequest:self.request]
                       delegate:self startImmediately:YES];
}

- (void)stopLoading
{
    NSLog(@">>>stopLoading");
    [self.connection cancel];
}

+ (NSArray *)targetURL
{
    static dispatch_once_t onceToken;
    static NSArray *__array = nil;
    dispatch_once(&onceToken, ^{
        __array = @[kLoadURLString,
                    kSampleGetURLString,
                    kSamplePostURLString];
    });
    return __array;
}

#pragma mark - NSURLConnectionDelegate

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

- (BOOL)connectionShouldUseCredentialStorage:(NSURLConnection *)connection {
    return YES;
}

- (void)connection:(NSURLConnection *)connection
didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    [[self client] URLProtocol:self didReceiveAuthenticationChallenge:challenge];
}

- (void)connection:(NSURLConnection *)connection
didCancelAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    [[self client] URLProtocol:self didCancelAuthenticationChallenge:challenge];
}

#pragma mark - NSURLConnectionDataDelegate

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

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

- (NSCachedURLResponse *)connection:(NSURLConnection *)connection
                  willCacheResponse:(NSCachedURLResponse *)cachedResponse
{
    return cachedResponse;
}

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

@end