backgroudDownload-05-网络后台下载

//
//  ViewController.m
//  05-backgroudDownload
//

#import "ViewController.h"

@interface ViewController () <NSURLSessionDownloadDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    NSURL *url = [NSURL URLWithString:@"http://218.76.27.57:8080/chinaschool_rs02/135275/153903/160861/160867/1370744550357.mp3"];
    
    //创建后台配置
//    NSURLSessionConfiguration *config = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"backdownloadTask"];
    NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
    
    //根据配置对象来创建后台Session
    NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:[NSOperationQueue mainQueue]];
    
    
    NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithURL:url];
    
    [downloadTask resume];
    
    
    
}

- (void)moveDownloadFile:(NSURL *)location ToPath:(NSString *)targetFilePath {
    
    //目标路径
    NSString *filePath = [NSHomeDirectory() stringByAppendingPathComponent:targetFilePath];
    
    NSFileManager *manager = [NSFileManager defaultManager];
    
    //判断目标路径下的文件是否存在，如果不存在，则剪切
    BOOL exist = [manager fileExistsAtPath:filePath];
    if (!exist) {
        
        [manager moveItemAtURL:location toURL:[NSURL fileURLWithPath:filePath] error:nil];
    }
    
    NSLog(@"文件保存成功");
    
    
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}


#pragma mark - NSURLSessionDownloadDelegate

//下载完成时调用
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location {
    
    NSLog(@"location:%@", location);
    
    
    //把临时目录下的文件剪切到目标文件夹。
    [self moveDownloadFile:location ToPath:@"Documents/jay.mp3"];
    
    
}

//监听下载进度，此协议方法可能会被调用多次
/*
 bytesWritten:本次传输下载了多少字节
 totalBytesWritten:已经下载了多少字节
 totalBytesExpectedToWrite：文件的总大小
 
 */
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
      didWriteData:(int64_t)bytesWritten
 totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {
    
    float progress = (float)totalBytesWritten / totalBytesExpectedToWrite;

    NSLog(@"下载%.2f%%", progress * 100);
    
    
}


@end