backgroudDownload-05-网络后台下载

 1 //
 2 //  ViewController.m
 3 //  05-backgroudDownload
 4 //
 5 
 6 #import "ViewController.h"
 7 
 8 @interface ViewController () <NSURLSessionDownloadDelegate>
 9 
10 @end
11 
12 @implementation ViewController
13 
14 - (void)viewDidLoad {
15     [super viewDidLoad];
16     // Do any additional setup after loading the view, typically from a nib.
17     
18     NSURL *url = [NSURL URLWithString:@"http://218.76.27.57:8080/chinaschool_rs02/135275/153903/160861/160867/1370744550357.mp3"];
19     
20     //创建后台配置
21 //    NSURLSessionConfiguration *config = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"backdownloadTask"];
22     NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
23     
24     //根据配置对象来创建后台Session
25     NSURLSession *session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:[NSOperationQueue mainQueue]];
26     
27     
28     NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithURL:url];
29     
30     [downloadTask resume];
31     
32     
33     
34 }
35 
36 - (void)moveDownloadFile:(NSURL *)location ToPath:(NSString *)targetFilePath {
37     
38     //目标路径
39     NSString *filePath = [NSHomeDirectory() stringByAppendingPathComponent:targetFilePath];
40     
41     NSFileManager *manager = [NSFileManager defaultManager];
42     
43     //判断目标路径下的文件是否存在，如果不存在，则剪切
44     BOOL exist = [manager fileExistsAtPath:filePath];
45     if (!exist) {
46         
47         [manager moveItemAtURL:location toURL:[NSURL fileURLWithPath:filePath] error:nil];
48     }
49     
50     NSLog(@"文件保存成功");
51     
52     
53 }
54 
55 - (void)didReceiveMemoryWarning {
56     [super didReceiveMemoryWarning];
57     // Dispose of any resources that can be recreated.
58 }
59 
60 
61 #pragma mark - NSURLSessionDownloadDelegate
62 
63 //下载完成时调用
64 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
65 didFinishDownloadingToURL:(NSURL *)location {
66     
67     NSLog(@"location:%@", location);
68     
69     
70     //把临时目录下的文件剪切到目标文件夹。
71     [self moveDownloadFile:location ToPath:@"Documents/jay.mp3"];
72     
73     
74 }
75 
76 //监听下载进度，此协议方法可能会被调用多次
77 /*
78  bytesWritten:本次传输下载了多少字节
79  totalBytesWritten:已经下载了多少字节
80  totalBytesExpectedToWrite：文件的总大小
81  
82  */
83 - (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
84       didWriteData:(int64_t)bytesWritten
85  totalBytesWritten:(int64_t)totalBytesWritten
86 totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite {
87     
88     float progress = (float)totalBytesWritten / totalBytesExpectedToWrite;
89 
90     NSLog(@"下载%.2f%%", progress * 100);
91     
92     
93 }
94 
95 
96 @end