iOS 网络与多线程－－6.下载并保存网络图片

使用二进制数据对象的,从制定网站获取数据的方法,下载网络图片,并转化为二进制数据,然后将二进制数据保存到磁盘

按照注释需要进行阅读以下代码

 //  Created by JinXin on 15/12/2.
 //  Copyright © 2015年 JinXin. All rights reserved.
 //

 #import "ViewController.h"

 @interface ViewController ()
 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view, typically from a nib.

     // 5.获取项目沙箱中的Documents文件夹。
     NSString *documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
             NSUserDomainMask, YES) objectAtIndex:];
     // 6.获取网络图片
     UIImage *imageFromURL = [self getImageFromURL:@"http://face.weiphone.net/data/avatar/001/27/35/59_avatar_big.jpg"];
     // 7.将图片保存到磁盘
     [self saveImage:imageFromURL withFileNmae:@"image" ofType:@"jpg" inDirectory:documentsDirectoryPath];
     // 7.输出路径
     NSLog(@"Path of saved image:%@",documentsDirectoryPath);

 }

 // 1.创建一个方法,用来获取网络图片,参数为图片的网络路径
 -(UIImage *)getImageFromURL:(NSString *)fileURL
 {
     NSLog(@"Getting image........");
     UIImage *result;

     // 2.获取网络图片,并将数据存入二进制数据对象
     NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileURL]];
     // 3.将二进制数据转为图像
     result = [UIImage imageWithData:data];
     // 4.返回结果
     return result;
 }

 // 2.创建一个方法,用来将图像保存到磁盘
 // 参数1.UIImage 对象
 // 参数2.文件名
 // 参数3.文件类型
 // 参数4.保存文件的路径
 -(void)saveImage:(UIImage *)image withFileNmae:(NSString *)imageName ofType:(NSString *)extension
      inDirectory:(NSString *)directoryPath
 {
     // 3.检测图片扩展名,如果是png后缀,则使用UIImagePNGRepresentation方法,将图片转为二进制数据,并写入磁盘
     if ([[extension lowercaseString] isEqualToString:@"png"])
     {
         [UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:
             [NSString stringWithFormat:@"%@.%@",imageName,@"png"]] options:NSAtomicWrite error:nil];
     }
     // 4. 检测图片扩展名,如果是jpg后缀,则使用UIImageJPEGRepresentation方法,将图片转为二进制数据,并写入磁盘
     else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"] )
     {
         [UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:
             [NSString stringWithFormat:@"%@.%@",imageName,@"jpg"]] options:NSAtomicWrite error:nil];
     }
 }

 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }

 @end

输出结果：

 -- ::47.132 AppDemo[:] Getting image........
 -- ::47.312 AppDemo[:] Path of saved image:/Users/jinxin/Library/Developer/CoreSimulator/Devices/78B0547C-FAC7--AAF0-EEB564932491/data/Containers/Data/Application/5051F20E--46DC-BC4E-C00D9F9CDDFF/Documents

之后打开finder 按Shift+Command+G 将路径粘贴进去 进入目录

将可以看到下载到的图片了