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:0];
    // 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：

2015-12-04 21:58:47.132 AppDemo[1030:104437] Getting image........
2015-12-04 21:58:47.312 AppDemo[1030:104437] Path of saved image:/Users/jinxin/Library/Developer/CoreSimulator/Devices/78B0547C-FAC7-4343-AAF0-EEB564932491/data/Containers/Data/Application/5051F20E-5736-46DC-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