NSURLSession实现断点下载
@interface
HMViewController
() <NSURLSessionDownloadDelegate,
NSURLSessionDataDelegate]]>
@property
(weak,
nonatomic)
IBOutlet
UIProgressView *progressView;
- (IBAction)download:(UIButton
*)sender;
@property
(nonatomic,
strong)
NSURLSessionDownloadTask
*task;
@property
(nonatomic,
strong)
NSData *resumeData;
@property
(nonatomic,
strong)
NSURLSession *session;
@end
@implementation
HMViewController
- (NSURLSession
*)session
{
if (!_session) {
//
获得session
NSURLSessionConfiguration
*cfg = [NSURLSessionConfiguration
defaultSessionConfiguration];
self.session
= [NSURLSession
sessionWithConfiguration:cfg
delegate:self
delegateQueue:[NSOperationQueue
mainQueue]];
}
return
_session;
}
- (IBAction)download:(UIButton
*)sender {
//
按钮状态取反
sender.selected
= !sender.isSelected;
if (self.task
==
nil) {
//
开始（继续）下载
if (self.resumeData)
{
//
恢复
[self
resume];
}
else {
//
开始
[self
start];
}
}
else {
//
暂停
[self
pause];
}
}
/**
*
从零开始
*/
- (void)start
{
// 1.创建一个下载任务
NSURL *url = [NSURL
URLWithString:@"http://192.168.15.172:8080/MJServer/resources/videos/minion_01.mp4"];
self.task
= [self.session
downloadTaskWithURL:url];
// 2.开始任务
[self.task
resume];
}
/**
*
恢复（继续）
*/
- (void)resume
{
//
传入上次暂停下载返回的数据，就可以恢复下载
self.task
= [self.session
downloadTaskWithResumeData:self.resumeData];
//
开始任务
[self.task
resume];
//
清空
self.resumeData
=
nil;
}
/**
*
暂停
*/
- (void)pause
{
__weak
typeof(self) vc =
self;
[self.task
cancelByProducingResumeData:^(NSData
*resumeData) {
// resumeData :
包含了继续下载的开始位置\下载的url
vc.resumeData
= resumeData;
vc.task
=
nil;
}];
}
#pragma mark - NSURLSessionDownloadDelegate
- (void)URLSession:(NSURLSession
*)session downloadTask:(NSURLSessionDownloadTask
*)downloadTask
didFinishDownloadingToURL:(NSURL
*)location
{
NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory,
NSUserDomainMask,
YES)
lastObject];
// response.suggestedFilename
：
建议使用的文件名，一般跟服务器端的文件名一致
NSString *file = [caches
stringByAppendingPathComponent:downloadTask.response.suggestedFilename];
//
将临时文件剪切或者复制Caches文件夹
NSFileManager *mgr = [NSFileManager
defaultManager];
// AtPath :
剪切前的文件路径
// ToPath :
剪切后的文件路径
[mgr
moveItemAtPath:location.path
toPath:file
error:nil];
}
- (void)URLSession:(NSURLSession
*)session downloadTask:(NSURLSessionDownloadTask
*)downloadTask
didWriteData:(int64_t)bytesWritten
totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
NSLog(@"获得下载进度--%@",
[NSThread
currentThread]);
//
获得下载进度
self.progressView.progress
= (double)totalBytesWritten / totalBytesExpectedToWrite;
}
- (void)URLSession:(NSURLSession
*)session downloadTask:(NSURLSessionDownloadTask
*)downloadTask
didResumeAtOffset:(int64_t)fileOffset
expectedTotalBytes:(int64_t)expectedTotalBytes
{
}