iOS下载文件和视频等多个任务

#import "ViewController.h"
#import "AFNetworking.h"


@interface ViewController ()
{
// 下载任务句柄
    NSURLSessionDownloadTask *_downloadTask;
    int downIndex;
    
}

@property (weak, nonatomic) IBOutlet UIProgressView *progressV;

@property (nonatomic, retain) NSArray  *urlArray;/**< 下载队列数组*/

@property (nonatomic, copy) NSString  *path;/**< */

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.urlArray = @[@"https://wkbos.bdimg.com/v1/wenku57//7b98301a2adf38c28ee0aef8921fda17?responseContentDisposition=attachment%3B%20filename%3D%22IOS%BF%AA%B7%A2%BB%B7%BE%B3%B4%EE%BD%A8%BA%CD%BC%F2%B5%A5%CA%B5%C0%FD.pdf%22&responseContentType=application%2Foctet-stream&responseCacheControl=no-cache&authorization=bce-auth-v1%2Ffa1126e91489401fa7cc85045ce7179e%2F2017-04-10T06%3A38%3A37Z%2F3600%2Fhost%2Feb0754e1d269be0ad50c2ebe78cf8f78ad065150edecfd731234e5374e7e5f84&token=da145c19277039627bf70015d9f111815fe86364ba0c387344f3b5d528a7f56b&expire=2017-04-10T07:38:37Z",
                      @"https://wkbos.bdimg.com/v1/wenku39//1d6911332cc6d657237bb02776868e05?responseContentDisposition=attachment%3B%20filename%3D%22iOS%BF%AA%B7%A2%D1%A7%CF%B0-%C8%E7%BA%CE%BC%F2%B5%A5%B5%C4%B4%EE%BD%A8%BB%B7%BE%B3.pptx%22&responseContentType=application%2Foctet-stream&responseCacheControl=no-cache&authorization=bce-auth-v1%2Ffa1126e91489401fa7cc85045ce7179e%2F2017-04-10T06%3A39%3A06Z%2F3600%2Fhost%2F24de87064b7f99a34e6e3e2ee7059d0b4225a2fb8f89ada0f300fb1b9b266567&token=4dcba41dff479e826c1ac3beeb9d282f62612d0f71ca1535dd404af062c6da79&expire=2017-04-10T07:39:06Z",
                      @"http://120.25.226.186:32812/resources/videos/minion_02.mp4",
                      @"http://120.25.226.186:32812/resources/images/minion_08.png"];
    
    downIndex = 0;
    
     NSString *urlSr = self.urlArray[0];
    //准备从远程下载文件
    [self downFileFromServer:urlSr];

}
//点击开始按钮启动下载任务
- (IBAction)beginDownLoading:(id)sender {
    //开始下载
    [_downloadTask resume];
}
- (IBAction)stopDownLoading:(id)sender {
    //暂停下载
    [_downloadTask suspend];
    
}

- (void)downFileFromServer:(NSString *)urlStr{
    __weak typeof(self) weakSelf = self;
    
    downIndex ++;
    if (urlStr.length <= 0) {
        //下载完成后 进行下一个任务
        if (downIndex < weakSelf.urlArray.count) {
            [weakSelf downFileFromServer:weakSelf.urlArray[downIndex]];
        }
        return ;
    }
    NSURL *URL = [NSURL URLWithString:urlStr];
    
    //默认配置
    NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
    
    //AFN3.0+基于封住URLSession的句柄
    AFURLSessionManager *manager = [[AFURLSessionManager alloc] initWithSessionConfiguration:configuration];
    //请求
    NSURLRequest *request = [NSURLRequest requestWithURL:URL];
    
    //下载Task操作
    _downloadTask = [manager downloadTaskWithRequest:request progress:^(NSProgress * _Nonnull downloadProgress) {

        // @property int64_t totalUnitCount;     需要下载文件的总大小
        // @property int64_t completedUnitCount; 当前已经下载的大小
//        downloadProgress.totalUnitCount;
//        downloadProgress.completedUnitCount;
        
        // 给Progress添加监听 KVO

        // 回到主队列刷新UI
        dispatch_async(dispatch_get_main_queue(), ^{
            // 设置进度条的百分比
            self.progressV.progress = 1.0 * downloadProgress.completedUnitCount / downloadProgress.totalUnitCount;
        });
        
    } destination:^NSURL * _Nonnull(NSURL * _Nonnull targetPath, NSURLResponse * _Nonnull response) {
        
        // 要求返回一个URL, 这个URL就是文件的位置的路径
        
        NSString *cachesPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
        NSString *path = [cachesPath stringByAppendingPathComponent:response.suggestedFilename];
        
        NSLog(@"文件路径：%@",path);
        self.path = path;
        return [NSURL fileURLWithPath:path];
        
    } completionHandler:^(NSURLResponse * _Nonnull response, NSURL * _Nullable filePath, NSError * _Nullable error) {
        //设置下载完成操作
        // filePath就是下载文件的位置, [filePath path];// 将NSURL转成NSString
 
        //下载完成后 进行下一个任务
        if (downIndex < weakSelf.urlArray.count) {
            weakSelf.progressV.progress = 0.0;
            [weakSelf downFileFromServer:weakSelf.urlArray[downIndex]];
            //开始下载
            [_downloadTask resume];
        }
       
    }];
}


@end