Question

我正在使用Parse和Facebook登录来创建新用户。我从Facebook获得了一些字段，比如他们的姓名和位置，请求他们在背景中加载他们的个人资料图片，然后再切换到我的主视图控制器，该控制器有一个PFImageView用于个人资料图像。

问题是，当主视图控制器的viewDidLoad触发时，PFFile用户[@＆＃34; profileImage＆＃34;]仍然是零，因此没有任何东西可以加载到背景中。

我不想在转到主视图控制器之前等待配置文件图像加载...这需要一些随机时间而且只是坏事。

那么，在我将它提供给PFFImageView之前，如何处理尚未加载的PFFile？某种占位符？

这是我的代码：

------- in LoginViewController.m

- (void) pressedFacebookLogin {
    [PFFacebookUtils logInWithPermissions...
        if(user.isNew) {
           FBRequest *request = [FBRequest requestForMe];
           [request startWithCompletionHandler:^(FBRequestConnection *connection, id result, NSError *error) {
                NSDictionary *userData = (NSDictionary *)result;    

                user[@"fullName"] = userData[@"name"];
                // get location, relationship if available
                [user saveInBackground];

                // start getting the user's profile image before going to main view controller
                NSURL *pictureURL = [NSURL URLWithString:[NSString stringWithFormat:@"https://graph.facebook.com/%@/picture?type=large&return_ssl_resources=1", facebookID]];
                NSURLRequest *urlRequest = [NSURLRequest requestWithURL:pictureURL];
                [NSURLConnection sendAsynchronousRequest:urlRequest queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {

                    if (connectionError == nil && data != nil) {
                        UIImage *tmpImage = [UIImage imageWithData:data];
                        NSData *imageData = UIImagePNGRepresentation(tmpImage);
                        PFFile *imageFile = [PFFile fileWithName:@"image.png" data:imageData];
                        user[@"profileImage"] = imageFile;
                        [user saveInBackground];
                    }
                }];

                [self segueToMainViewController];

           }];
        }else {
             // deal with existing user...
        }
    }];
}

-------------- in MainViewController.m

- (void) viewDidLoad {
    [super viewDidLoad];

    PFUser *user = [PFUser currentUser];

    self.profileImageView.image = [UIImage imageNamed:@"placeholder"];
    PFFile *profileImageFile = user[@"profileImage"];
    // at this point profileImageFile is nil
    self.profileImageView.file = profileImageFile;
    [self.profileImageView loadInBackground];

}

Answer 1

在将profileImageFile设置为空的位置添加此行。

我猜你使用的profileImageView是一个ImageView。

@property (weak, nonatomic) IBOutlet UIImageView *profileImageView;

// at this line where you get profileImageFile as nil
[self.profileImageView setImageWithURL:[NSURL URLWithString:user[@"profileImage"]] placeholderImage:[UIImage imageNamed:@"default_profileImage"]];

附加到PFImageView之前未加载PFFile图像？

1 个答案: