实现协议NSURLSessionDownloadDelegate的2个方法
此方法主要返回文件的字节数以及已下载的字节数
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite;
储存的零时文件路径location
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location;
样式图，由于网速太快，手速跟不上，加载图片太快没来得及点击暂停下载以及就加载出来了，大家如果想实现可以把路径改为一个大一点的文件，这样就能看的很明显了。
屏幕快照 2016-04-14 下午1.33.37.png
屏幕快照 2016-04-14 下午1.32.49.png
代码实现
#import "ViewController.h"
@interface ViewController () <NSURLSessionDownloadDelegate>
@property (weak, nonatomic) IBOutlet UIImageView *loadImage;
@property (weak, nonatomic) IBOutlet UIProgressView *progress;
@property (weak, nonatomic) IBOutlet UILabel *loadPlan;
@property (weak, nonatomic) IBOutlet UIButton *loadTitle;
@property (nonatomic, strong) NSData *data;
@property (nonatomic, strong) NSURLSession *session;
@property (nonatomic, strong) NSURLSessionDownloadTask *task;
@property (nonatomic, assign) BOOL judgeDown;
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/**
* 下载的字节
*
* @param session session
* @param downloadTask taskdownload
* @param bytesWritten 每次下载的字节
* @param totalBytesWritten 已下载的字节
* @param totalBytesExpectedToWrite 总字节
*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{
//进度条计算
CGFloat progress = (totalBytesWritten*1.0)/totalBytesExpectedToWrite;
//异步添加到主队列下载
dispatch_async(dispatch_get_main_queue(), ^{
_progress.progress = progress;
_loadPlan.text = [NSString stringWithFormat:@"开始下载：%d/100",(int)(progress*100)];
}) ;
}
/**
* NSURLSessionDownloadDelegate委托协议
*
* @param session session
* @param downloadTask sessiontask
* @param location 储存的零时文件路径
*/
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location{
NSFileManager *manager = [NSFileManager defaultManager];
//获取document目录
NSString *strDocument = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).lastObject;
//在原有路径上添加路径
NSString *strURL = [strDocument stringByAppendingPathComponent:@"1250538257738.jpg"];
//本地URL路径
NSURL *url = [NSURL fileURLWithPath:strURL];
if ([manager fileExistsAtPath:strURL]) {
[manager removeItemAtPath:strURL error:nil];
}
//把tem文件移动指定的URL路径上
if ([manager moveItemAtURL:location toURL:url error:nil]) {
_data = [manager contentsAtPath:strURL];
_loadImage.image = [UIImage imageWithData:_data];
}
}
- (IBAction)onClick:(id)sender {
NSString *strURL = @"http://img.pconline.com.cn/images/bbs4/20098/18/1250538257738.jpg";
NSURL *url = [NSURL URLWithString:strURL];
//创建config对象
NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
//创建session对象，并添加到主队列中
_session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:[NSOperationQueue mainQueue]];
//下载路径
_task = [_session downloadTaskWithURL:url];
[_task resume];
}
- (IBAction)suspendLoad:(id)sender {
if (_judgeDown) {
NSLog(@"恢复下载");
_loadTitle.titleLabel.text = @"暂停下载";
if(!_data){
NSURL *url = [NSURL URLWithString:@"http://img.pconline.com.cn/images/bbs4/20098/18/1250538257738.jpg"];
// _request = [NSURLRequest requestWithURL:url];
// _task = [_session downloadTaskWithRequest:_request];
_task = [_session downloadTaskWithURL:url];
}else{
_task = [_session downloadTaskWithResumeData:_data];
}
[_task resume];
}else{
NSLog(@"暂停下载");
_loadTitle.titleLabel.text = @"恢复下载";
//取消下载并调用回调与恢复数据供以后使用
[_task cancelByProducingResumeData:^(NSData *resumeData) {
_data = resumeData;
}];
_task = nil;
_judgeDown = YES;
}
}
@end
