如何使用 NSURLSession 保存 Facebook 个人资料图片？

Posted 2023-03-16

【中文标题】如何使用 NSURLSession 保存 Facebook 个人资料图片？

【英文标题】：How do I save a facebook profile picture using NSURLSession?

【发布时间】：2016-02-19 12:21:36

【问题描述】：

我只是在创建一个简单的 facebook 登录应用程序，在我的 viewdidload() 方法中，我拥有权限并且我正在获取名称、用户名、电子邮件 ID 和个人资料图片链接，但我想做的是尝试下载该链接（URL）并在本地保存/下载。

刚开始使用 x-code，如有任何帮助，将不胜感激。

> - (void)viewDidLoad 
>     
>      [super viewDidLoad];    
>     FBSDKLoginButton *loginButton = [[FBSDKLoginButton alloc] init];    loginButton.center = self.view.center;    [loginButton
> setDelegate:self];
>     loginButton.loginBehavior=FBSDKLoginBehaviorWeb;
>         [self.view addSubview:loginButton];
>     loginButton.readPermissions = @[@"public_profile",@"email",@"user_friends",@"user_about_me",@"user_friends",@"user_birthday",@"user_hometown"];
>     loginButton.publishPermissions=@[@"publish_actions"];
>     FBSDKLoginManagerLoginResult *result;
>     
>     
> 
>     
>         if ([result.grantedPermissions containsObject:@"email"]) 
>             NSLog(@"%@",result);
>         
>     
> 
>     NSMutableDictionary* param = [NSMutableDictionary dictionary];
>     [param setValue:@"id,name,email,picture.width(100).height(100),bio"
> forKey:@"fields"];
> 
> 
>     NSURL *profilePictureURL = [NSURL URLWithString:[NSString stringWithFormat:@"https://graph.facebook.com/user/picture?type=large"]];
>                                                       NSURLRequest *profilePictureURLRequest = [NSURLRequest requestWithURL:profilePictureURL
> cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10.0f];
> // Facebook profile picture cache policy: Expires in 2 weeks
>     [NSURLSession sessionWithConfiguration:profilePictureURLRequest delegate:self delegateQueue:nil];

【参考方案1】：

试试这个代码，它会将图像保存在应用程序文档目录中。

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^
                    NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:[NSString stringWithFormat:@"https://graph.facebook.com/%@/picture?type=normal",[result objectForKey:@"id"]]]];
                    [imageData writeToFile:[NSString stringWithFormat:@"%@/profilePic.jpg",[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0]] atomically:YES];
                )

【参考方案2】：

使用您的NSURLRequest 创建一个NSURLSessionDataTask 任务：

NSURL *profilePictureURL = ...;
NSURLRequest *profilePictureURLRequest = ...;

NSURLSession *session = [NSURLSession sharedSession];
NSURLSessionDataTask *task = [session dataTaskWithRequest:profilePictureURLRequest completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) 

    // This block is called when the request completes / fails.

    if ((!error) && (data.length > 0)) 

        // Write to local URL on background thread.
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^

            NSURL *someFileUrl = ...;

            [data writeToUrl:someFileUrl atomically:YES];

        );
    
];

// Send the request...
[task resume];