objective-c URLSession download class

downloader.m

//
//  FileDownloader.m
//

#import <Foundation/Foundation.h>
#import "FileDownloader.h"
#import "NSMutableArray+QueueAdditions.h"


@interface FileDownloader()

@property NSInteger downloadSize;
@property NSInteger pendingDownloadSize;
@property long bytesReceived;
@property NSString* outPutPath;
@property NSMutableArray *queue;
@property NSString *path;
@property NSURLSessionConfiguration *defaultConfigObject;
@property NSURLSession *defaultSession;
@property NSURLSessionDataTask *dataTask;
@property NSFileHandle *currentHandle;

@end

@implementation FileDownloader : NSObject


-(instancetype) initWithDir: (NSString*) path {
    self = [super init];
    _path = path;
    _queue = [[NSMutableArray alloc] init];
    _defaultConfigObject = [NSURLSessionConfiguration defaultSessionConfiguration];
    _defaultSession = [NSURLSession sessionWithConfiguration: _defaultConfigObject delegate: self delegateQueue: [NSOperationQueue mainQueue]];
    return self;
}

-(void) downloadFile: (NSURL*) url {
    [_queue enqueue:url];
    if(_dataTask == nil){
        id ur = [_queue dequeue];
        if(ur != nil){
            _dataTask = [_defaultSession dataTaskWithURL: url];
            [_dataTask resume];
        }
    }
}

-(void) next {
    id url = [_queue dequeue];
    
    if(url != nil){
        _dataTask = [_defaultSession dataTaskWithURL: url];
        [_dataTask resume];
    } else {
        _dataTask = nil;
        
        
    }
    
}

-(void) cancel {
    
    [_queue removeAllObjects];
    [_dataTask cancel];
}


- (void)URLSession:(NSURLSession *)session
              task:(NSURLSessionTask *)task
willPerformHTTPRedirection:(NSHTTPURLResponse *)response
        newRequest:(NSURLRequest *)request
 completionHandler:(void (^)(NSURLRequest *))completionHandler {
    NSLog(@"willPerformRedirection");
    completionHandler(request);

}


- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {
    
    completionHandler(NSURLSessionResponseAllow);
    _downloadSize = [response expectedContentLength];
    NSLog(@"didReceiveResponse %ld",_downloadSize);
    NSString *file = [_path stringByAppendingPathComponent:[response suggestedFilename]];
    [[NSFileManager defaultManager] createFileAtPath:file contents:[[NSData alloc] init] attributes:nil];
    _currentHandle =  [NSFileHandle fileHandleForWritingAtPath: file];

}

- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
    
    _bytesReceived += [data length];
    [self->_currentHandle writeData:data];
}

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
   
    if(error != nil) {
        NSLog(@"%@",error.localizedDescription);
    }
    [self next];
    
    
}

@end