Question

我对objective-c有点新，我正在开发一个新闻iOS应用程序，该应用程序使用来自URL的JSON解析获取其所有内容，我使用AFNetworking为此，这是我做的方法：

- (void)getContents
{
    NSString *urlString = @"http://some-url-that-has-json-output/";
    urlString = [urlString stringByAppendingString:self.articleId];
    NSLog(@"The call url is: %@",urlString);
    NSURL *url = [NSURL URLWithString:urlString];

    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    //AFNetworking asynchronous url request
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc]
                                         initWithRequest:request];
    operation.responseSerializer = [AFJSONResponseSerializer serializer];
    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        NSLog(@"The JSON data is: %@", responseObject);
        jsonContents = [responseObject objectForKey:@"article"];
        [self LoadStructure];
    } failure:nil];
    [operation start];
}

现在，使用此方法可以很好地加载数据。

我的问题：如何在获取数据时显示加载指示符（可能是GIF）？以上这种方法是从网址获取数据的正确或最佳方法吗？

Answer 1

您可以使用iOS的默认加载指示符（UIActivityIndicator）。您应该在完成块之前开始设置动画，并且应该隐藏在成功和失败块中。

您应该使用指标作为类变量创建一个方法：

indicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
indicator.hidesWhenStopped = YES;
indicator.frame = CGRectMake(35, 15, 30, 30);
[self.view addSubview:indicator];

NSURLRequest *request = [NSURLRequest requestWithURL:url];
//AFNetworking asynchronous url request
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc]
                                     initWithRequest:request];
operation.responseSerializer = [AFJSONResponseSerializer serializer];
[indicator startAnimating];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"The JSON data is: %@", responseObject);

//停止：

[indicator stopAnimating];
    jsonContents = [responseObject objectForKey:@"article"];
    [self LoadStructure];
} failure::^(AFHTTPRequestOperation *operation, NSError *error){
    [indicator stopAnimating];
}];
[operation start];

Answer 2

将UIActivityIndicatorView拖放到XIB视图中，并将其与IBOutlet连接。

.h文件

@property(nonatomic, strong)IBOutlet UIActivityIndicatorView * activityIndicator;

在视图中添加UIActivity指示器视图。在

之前展示

NSString *urlString = @"http://some-url-that-has-json-output/";

使用：[self.activityIndicator startAnimating];

并在完成块和故障块中停止

使用：[self.activityIndicator stopAnimating];

在从URL获取数据时显示加载指示符的正确方法是什么

2 个答案: