內存警告下載文件，AFNetworking

我寫了一個非常簡單的下載代碼：

NSArray  *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
NSString *documentsDirectory = [paths objectAtIndex:0]; 

NSURLRequest* request = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"http://xxxx.s3.amazonaws.com/products/ipad/xxxx.mp4"]]; 
for(int i=0; i<4; i++){ 
    NSString *filePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory,[NSString stringWithFormat:@"xxxx%d.mp4",i]]; 
    AFDownloadRequestOperation* operation = [[AFDownloadRequestOperation alloc] initWithRequest:request targetPath:filePath shouldResume:YES]; 
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:filePath append:NO]; 
    [operation setShouldOverwrite:YES]; 
    [operation setProgressiveDownloadProgressBlock:^(AFDownloadRequestOperation *operation, NSInteger bytesRead, long long totalBytesRead, long long totalBytesExpected, long long totalBytesReadForFile, long long totalBytesExpectedToReadForFile) { 
     NSLog(@"%f", (totalBytesRead/(float)totalBytesExpected)); 
    }]; 
    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) { 
     NSLog(@"finished"); 
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) { 
     NSLog(error.description); 
    }]; 
    [[NSOperationQueue mainQueue] addOperation:operation]; 
}

我寫在我的項目viewDidLoad中註釋掉所有其他代碼。內存使用仍然是相同的，增加：

我創建了一個新的項目，我在新的項目中寫道完全相同的代碼。和內存使用情況是：

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