NSUrlSession下载图片

//
//  ViewController.m
//  UrlSession
//
//  Created by dc0061 on 15/12/10.
//  Copyright © 2015年 dc0061. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()
{
    UILabel *_url;
    UILabel *tishi;
    
    UITextField *_urlName;//输入框，输入url
    
    UIImageView *_image;
    //添加按钮
    UIButton *_xiazai;
    UIButton *_quxiao;
    UIButton *_guaqi;
    UIButton *_huifu;
    UIProgressView *pro;//进度条
    NSURLSessionDownloadTask *_download;
}
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self layout];
}
//加载控件
- (void) layout{
    _url= [[UILabel alloc]initWithFrame:CGRectMake(40, 50, 50, 40)];
    _url.text=@"网址";
    _url.textColor=[UIColor redColor];
    [self.view addSubview:_url];
    
    _urlName=[[UITextField alloc]initWithFrame:CGRectMake(100, 50, 250, 40)];
    _urlName.borderStyle=UITextBorderStyleRoundedRect;//设置边框样式
    _urlName.text=@"http://dlsw.baidu.com/sw-search-sp/soft/2a/25677/QQ_V4.0.5.1446465388.dmg";
//    _urlName.text=@"http://img15.3lian.com/2015/f2/52/d/45.jpg";
    [self.view addSubview:_urlName];
    
    _image=[[UIImageView alloc]initWithFrame:CGRectMake(40, 120, 300, 400)];
    _image.image=[UIImage imageNamed:@"2"];
    [self.view addSubview:_image];
    
    pro=[[UIProgressView alloc]initWithFrame:CGRectMake(40, 570, 200, 20)];
    [self.view addSubview:pro];
    
    tishi=[[UILabel alloc]initWithFrame:CGRectMake(250, 550, 100, 40)];
    tishi.font=[UIFont systemFontOfSize:10];
    tishi.text=@"正在下载。。。";
    tishi.textColor=[UIColor redColor];
    [self.view addSubview:tishi];
    
    _dowenloadFile=[[UIButton alloc]initWithFrame:CGRectMake(20, 600, 80, 50)];
    [_dowenloadFile setTitle:@"简化下载" forState:UIControlStateNormal];
    [_dowenloadFile setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [_dowenloadFile addTarget:self action:@selector(dowenloadFile) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_dowenloadFile];
    
    _xiazai=[[UIButton alloc]initWithFrame:CGRectMake(110, 600, 50, 50)];
    [_xiazai setTitle:@"下载" forState:UIControlStateNormal];
    [_xiazai setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [_xiazai addTarget:self action:@selector(xiazai) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_xiazai];
    
    _quxiao=[[UIButton alloc]initWithFrame:CGRectMake(170, 600, 50, 50)];
    [_quxiao setTitle:@"取消" forState:UIControlStateNormal];
    [_quxiao setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [_quxiao addTarget:self action:@selector(quxiao) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_quxiao];
    
    _guaqi=[[UIButton alloc]initWithFrame:CGRectMake(230, 600, 50, 50)];
    [_guaqi setTitle:@"挂起" forState:UIControlStateNormal];
    [_guaqi setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [_guaqi addTarget:self action:@selector(guaqi) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_guaqi];
    
    _huifu=[[UIButton alloc]initWithFrame:CGRectMake(290, 600, 50, 50)];
    [_huifu setTitle:@"恢复" forState:UIControlStateNormal];
    [_huifu setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    [_huifu addTarget:self action:@selector(huifu) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:_huifu];
}


- (void) xiazai{
    NSLog(@"下载");
    //创建一个URL
    NSString *urlstr=_urlName.text;
    urlstr=[urlstr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
    
    NSURL *url=[NSURL URLWithString:urlstr];
    //创建请求
    NSURLRequest *request=[NSURLRequest requestWithURL:url];
    //创建session:  NSURLSessionConfiguration配置session  (默认会话  单例)
    NSURLSessionConfiguration *sessionConfig=[NSURLSessionConfiguration defaultSessionConfiguration];
    sessionConfig.timeoutIntervalForRequest=20;//请求超时时间
//    sessionConfig.timeoutIntervalForResource=20;//资源超时时间
    //是否允许蜂窝网络下载（2G/3G/4G）   NO: 只能在WiFi的情况下下载
    sessionConfig.allowsCellularAccess=YES;
    
    //创建会话   指定配置和代理
    NSURLSession *session=[NSURLSession sessionWithConfiguration:sessionConfig delegate:self delegateQueue:nil];
    _download=[session downloadTaskWithRequest:request];
    //恢复任务
    [_download resume];
}
- (void) quxiao{
    NSLog(@"取消");
    [_download cancel];
}
- (void) guaqi{
    NSLog(@"挂起");
    [_download suspend];
}
- (void) huifu{
    NSLog(@"恢复");
    [_download resume];
}
//更新进度条
- (void) setprogress : (int64_t)totalBytesWritten :(int64_t) totalBytesExpectedToWrite{
    //异步处理进程   (dispatch_get_main_queue())获取主队列
    dispatch_async(dispatch_get_main_queue(), ^{
        pro.progress=(float)totalBytesWritten/totalBytesExpectedToWrite;
        if (pro.progress==1) {
            tishi.text=@"下载完成";
            [UIApplication sharedApplication].networkActivityIndicatorVisible=NO;//屏幕左上角的菊花
        }else{
            [UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
        }
    });
}
//后面三个参数代表:当前下载量，总的下载量，下载文件的总大小
#pragma  mark 下载中会多次调用，可以用来记录进度条    这个是代理中的方法
- (void) URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{
    [self setprogress:totalBytesWritten :totalBytesExpectedToWrite];//更新进度条
}

#pragma mark  下载完成会调用的方法
- (void)URLSession:(NSURLSession *)session downloadTask:(nonnull NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(nonnull NSURL *)location{
    NSString *path=[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)lastObject];
    path=[path stringByAppendingPathComponent:@"qq1.dmg"];
    NSURL *saveUrl=[NSURL fileURLWithPath:path];//转换成本地的url使用 fileURLWithPath
    //复制文件，从location 拷贝到我想要的位置
    NSError *error;
    [[NSFileManager defaultManager] copyItemAtURL:location toURL:saveUrl error:&error];
    if(error){
        NSLog(@"error : %@",error.localizedDescription);
    }
}

#pragma  mark 不管下载成功与否，都会调用

- (void) URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error{
    if (error) {
        NSLog(@"error : %@", error.localizedDescription);
    }else{
        NSLog(@"无错误");
    }
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

@end