Alexander

[NSURLProtocol registerClass:[MP3DetectURLProtocol class]];

#import <Foundation/Foundation.h>

@interface MP3DetectURLProtocol : NSURLProtocol

@property (nonatomic, strong) NSURLConnection *connection;

@end

#import "MP3DetectURLProtocol.h"

@implementation MP3DetectURLProtocol

static NSString *PBProxyURLHeader = @"X-PB";

+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
    //if([[request.URL absoluteString] rangeOfString:@"mp3"].length !=0)
        NSLog(@"request url = %@", [request.URL absoluteString]);
    if ([request valueForHTTPHeaderField:PBProxyURLHeader] == nil)
    {
        return YES;
    }
    return NO;
}

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

- (void) startLoading
{
    NSMutableURLRequest *newRequest = [self.request mutableCopy];
    [newRequest setValue:@"" forHTTPHeaderField:PBProxyURLHeader];
    // Here we set the User Agent
    //[newRequest setValue:@"Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.2 Safari/537.36 Kifi/1.0f" forHTTPHeaderField:@"User-Agent"];
    
    //[NSURLProtocol setProperty:@YES forKey:@"UserAgentSet" inRequest:newRequest];
    //NSLog(@"start loading");
    self.connection = [NSURLConnection connectionWithRequest:newRequest delegate:self];
}

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

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

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

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

- (NSURLRequest *)connection:(NSURLConnection *)connection
             willSendRequest:(NSURLRequest *)request
            redirectResponse:(NSURLResponse *)response
{
    [self.client URLProtocol:self wasRedirectedToRequest:request redirectResponse:response];
    return nil;
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    [self.client URLProtocolDidFinishLoading:self];
    self.connection = nil;
}

@end

NSString *dir = [pathCache stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.download", [itemToDownload fileName]]];
    if(data)
        [tmpData appendData:data];
    if(![tmpData length])
        return;
    NSFileHandle *handle = [NSFileHandle fileHandleForWritingAtPath:dir];
    [handle seekToEndOfFile];
    [handle writeData:tmpData];
    [handle closeFile];
    [tmpData setLength:0];