在重新加载之前删除表格行

Question

我想在重新加载数据之前删除表格视图中的所有行，但似乎无法使其工作。

在我的viewcontroller中，我从这个AFNetworking请求中获得我的数组。

- (void)viewDidLoad 
    [[LocationApiClient sharedInstance] getPath:@"locations.json" 
            parameters:nil 
             success: 
       ^(AFHTTPRequestOperation *operation, id response) { 
        NSLog(@"Response: %@", response); 
        NSMutableArray *location_results = [NSMutableArray array]; 
        for (id locationDictionary in response) { 
         Location *location = [[Location alloc] initWithDictionary:locationDictionary]; 
         [location_results addObject:location]; 
        } 
        self.location_results = location_results; 
        [self.tableView reloadData]; 
        } 
            failure: 
       ^(AFHTTPRequestOperation *operation, NSError *error) { 
        NSLog(@"Error fetching locations!"); 
        NSLog(@"%@", error); 
       }]; 
} 

而且我想删除的数据，然后通过这个按钮

- (IBAction)locationPressed:(id)sender { 

    [[Location sharedSingleton].locationManager startUpdatingLocation]; 
    [self viewDidLoad]; 
    NSMutableArray *location_results = [NSMutableArray array]; 
    [location_results removeAllObjects]; 
    [self.tableView reloadData]; 

} 

重新加载它，但它不删除行。我看到重载发生在已经存在的行的顶部。有什么建议么？

Answer 1

请千万不要手动拨打viewDidLoad。

创建像

- (void)reloadDataWithCompletion:(void(^)(NSArray *locations))completion 
         failure:(void(^)(NSError *error))failure { 
    [[LocationApiClient sharedInstance] getPath:@"locations.json" 
            parameters:nil 
             success: 
      ^(AFHTTPRequestOperation *operation, id response) { 
       NSLog(@"Response: %@", response); 
       NSMutableArray *location_results = [NSMutableArray array]; 
       for (id locationDictionary in response) { 
        Location *location = [[Location alloc] initWithDictionary:locationDictionary]; 
        [location_results addObject:location]; 
       } 
        if(completion) 
         completion(location_results); 
       } 
           failure: 
      ^(AFHTTPRequestOperation *operation, NSError *error) { 
       if(failure) 
        failure(error); 
      }]; 
} 

的方法，并调用它时，你需要重新加载数据

- (void)viewDidLoad { 
    [super viewDidLoad]; // Don't forget the call to super! 

    [self reloadDataWithCompletion:^(NSArray *locations) { 
     self.location_results = locations; 
     [self.tableView reloadData]; 
    } failure:^(NSError *error) { 
     NSLog(@"Error fetching locations!"); 
     NSLog(@"%@", error); 
    }]; 
} 

- (IBAction)locationPressed:(id)sender { 
    [[Location sharedSingleton].locationManager startUpdatingLocation]; 
    [self reloadDataWithCompletion:^(NSArray *locations) { 
     self.location_results = locations; 
     [self.tableView reloadData]; 
    } failure:^(NSError *error) { 
     NSLog(@"Error fetching locations!"); 
     NSLog(@"%@", error); 
    }]; 
} 

为了实现重载，你可以做表的图形效果（假设你只有一个部分），替代品

[self.tableView reloadData]; 

与

[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationFade];