Question

我正在尝试通过将self.neighbourData过滤到self.closeByNeighbours（一个新数组）中来创建一个新数组，并且一切正常，数据将在viewDidLoad中显示。但是，当尝试返回self.closeByNeighbours的单元格数量时，NSArray计数是否返回NULL？为什么会这样？

ViewController.h

@property (strong, nonatomic) NSArray *closeByNeighbours;
@property (strong, nonatomic) NSMutableArray *neighbourData;

ViewController.m

    -(void)viewDidLoad {

      NSMutableDictionary *viewParams = [NSMutableDictionary new];
        [viewParams setValue:@"u000" forKey:@"view_name"];
        [DIOSView viewGet:viewParams success:^(AFHTTPRequestOperation *operation, id responseObject) {


            self.neighbourData = [responseObject mutableCopy];
             [self.neighboursView reloadData];


            NSDictionary *userDictInfo = (NSDictionary*) [NSKeyedUnarchiver unarchiveObjectWithData:[[NSUserDefaults standardUserDefaults] objectForKey:@"diosSession"]];

            DIOSSession *session = [DIOSSession sharedSession];
            [session setUser:userDictInfo];


            [session user];


            NSString *myData = [session user][@"user"][@"field_province"][@"und"][0][@"safe_value"];

            self.closeByNeighbours = [self.neighbourData filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(province contains[c] %@)", myData]];



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

    }

- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{


    if (tableView == self.neighboursView) {

        return [self.closeByNeighbours count];


    }

}

Answer 1

该框架确实在视图加载后隐式重新加载了表视图。

那时closeByNeighbours被声明但未初始化，因此它是nil。

viewGet中的完成块将在稍后调用。

避免使用nil的解决方案是在viedDidLoad的开头初始化数组

-(void)viewDidLoad {
    [super viewDidLoad];
    self.closeByNeighbours = [NSArray array];
    ...

并且您必须在完成处理程序中的主线程上重新加载表视图

...
self.closeByNeighbours = [self.neighbourData filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(province contains[c] %@)", myData]];
dispatch_async(dispatch_get_main_queue(), ^{
    [self.tableView reloadData];
});

Answer 2

我认为您忘记了初始化closeByNeighbours。尝试添加。

NSString *myData = [session user][@"user"][@"field_province"][@"und"][0][@"safe_value"];
self.closeByNeighbours = [NSArray array: filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(province contains[c] %@)", myData]];

或者，根据需要，您只需要初始化closeByNeighbours属性。

OBJ-C-NSArray属性在numberOfRowsInSection中显示为NULL，但在viewDidLoad中不显示？

2 个答案: