UITableView方法被调用之前ViewDidLoad

问题描述：

我试图创建一个简单的天气应用程序，它使用JSON从OpenweatherMap获取数据并在UITableView中打印出来。但是，当我在下面执行此代码并在numberOfRowsInSection方法中设置断点时，它将返回0行。不知怎的，viewDidLoad方法在numberOfRowsInSection方法之后被调用，这就是threeHoursForecast数组为空的原因。任何人都可以帮助我吗？UITableView方法被调用之前ViewDidLoad

static NSString * const BaseURLString = @"http://api.openweathermap.org/data/2.5/forecast?q=Houston"; 

@interface HPViewController() 

@end 

@implementation HPViewController 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) { 
     // Custom initialization 
    } 
    return self; 
} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

    self.threeHoursForecast = [[NSMutableArray alloc] init]; 
    self.tableView.dataSource = self; 
    self.tableView.delegate = self; 

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager]; 

    [manager POST:BaseURLString parameters:nil 
      success:^(AFHTTPRequestOperation *operation, id responseObject) { 

       NSArray *data = [responseObject objectForKey:@"list"]; 

       for (NSDictionary *forecastPerThreeHours in data) 
        [self.threeHoursForecast addObject:[[forecastPerThreeHours valueForKey:@"main"] valueForKey:@"temp"]]; 
      } 

      failure:^(AFHTTPRequestOperation *operation, NSError *error) { 

       NSLog(@"Error: %@", error); 
      }]; 

} 

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

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{ 
    // Return the number of sections. 
    return 1; 
} 

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    // Return the number of rows in the section. 
    return [self.threeHoursForecast count]; 
}

答

您可以在调用完成处理程序后重新载入数据，这将解决问题。

[manager POST:BaseURLString parameters:nil 
      success:^(AFHTTPRequestOperation *operation, id responseObject) { 

       NSArray *data = [responseObject objectForKey:@"list"]; 

       for (NSDictionary *forecastPerThreeHours in data) 
        [self.threeHoursForecast addObject:[[forecastPerThreeHours valueForKey:@"main"] valueForKey:@"temp"]]; 

       //Add this line 
       [self.TableView reloadData]; 
      } 

      failure:^(AFHTTPRequestOperation *operation, NSError *error) { 

       NSLog(@"Error: %@", error); 
      }];

谢谢。它现在有效。我曾尝试重新加载数据，但我把它放在请求的成功块之外，所以它不起作用 – Harry 2014-10-02 16:10:10

答

post方法是异步的。您需要在连续的请求中添加[self.tableView reloadData];。

谢谢。它现在有效。我曾尝试重新加载数据，但我把它放在请求的成功块之外，所以它不起作用 – Harry 2014-10-02 16:10:31

答

manager POST:是异步调用，因此您需要在获取JSON后重新载入数据。

[manager POST:BaseURLString parameters:nil 
       success:^(AFHTTPRequestOperation *operation, id responseObject) { 

        NSArray *data = [responseObject objectForKey:@"list"]; 

        for (NSDictionary *forecastPerThreeHours in data) 
         [self.threeHoursForecast addObject:[[forecastPerThreeHours valueForKey:@"main"] valueForKey:@"temp"]]; 

        // [NOTE] 
        [self.tableView reloadData]; 
       } 

       failure:^(AFHTTPRequestOperation *operation, NSError *error) {  
        NSLog(@"Error: %@", error); 
       }];

UITableView方法被调用之前ViewDidLoad

相关推荐