iOS學習-10下載(2)NSURLSession 篇

使用NSURLSessionDownloadTask下載文件的過程與前面差不多，需要註意的是文件下載文件之後會自動保存到一個臨時目錄，需要開發人員自己將此文件重新放到其他指定的目錄中。

//
//  ViewController.m
//  NSURLSession
//
//  Copyright © 2016年 asamu. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self downLoadFile];
}

-(void)downLoadFile{
//1.創建 url
    NSString *fileName = @"1.jpg";
    NSString *urlStr = [NSString stringWithFormat:@"http://img3.douban.com/lpic/s4717862.jpg",fileName];
    urlStr  = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    NSURL *url = [NSURL URLWithString:urlStr];
    //2.創建請求
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    //創建會話
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDownloadTask *downloadTask = [session downloadTaskWithRequest:request completionHandler:^(NSURL * _Nullable location, NSURLResponse * _Nullable response, NSError * _Nullable error) {
        if(!error){
        //location 是下載後的臨時保存路徑，需要將它移動到需要保存的位置
        NSError *saveError = nil;
        NSString *cachePath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES)lastObject];
        NSString *savePath = [cachePath stringByAppendingString:fileName];
        NSLog(@"%@",savePath);
        NSURL *url = [NSURL fileURLWithPath:savePath];
        
        [[NSFileManager defaultManager]copyItemAtURL:location toURL:url error:&saveError];
        if (!saveError) {
            NSLog(@"save success");
        }else{
            NSLog(@"error is :%@",saveError.localizedDescription);
        }
        }else{
            NSLog(@"error is :%@",error.localizedDescription);
        }
    }];
    //執行任務
    [downloadTask resume];
}

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

@end

來自KenshinCui,鏈接見上篇。