Question

嗨，当我执行for循环以从集合中获取所有文档时。我将汽车对象添加到NSMutablearray中，当我调试时，我可以看到对象正在添加到数组中，但是当我希望它在表中显示并获取数组的计数时，我将其称为[self.mycars count]获取计数，但计数为零，我无法从cell.textLabel.text = vehicle.name获取信息；所以我做错了。

#import "TableViewController.h"
#import "Car.h"
#import "Vehicle.h"

@interface TableViewController ()

@end

@implementation TableViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Uncomment the following line to preserve selection between presentations.
    // self.clearsSelectionOnViewWillAppear = NO;

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;

    self.db = [FIRFirestore firestore];
    self.myCars = [[NSMutableArray alloc] init];


    [[[[self.db collectionWithPath:@"users"] documentWithPath:[FIRAuth auth].currentUser.uid]
      collectionWithPath:@"cars"] getDocumentsWithCompletion:^(FIRQuerySnapshot *snapshot, NSError *error) {
        if (error != nil) {
            NSLog(@"Error getting documents: %@", error);
        } else {
            for (FIRDocumentSnapshot *document in snapshot.documents) {
                NSLog(@"%@ => %@", document.documentID, document.data);
                Car *car = [[Car alloc] initWithCarName:[document valueForField:@"carname"] andCarStyle:[document valueForField:@"carstyle"]
                                           andCarColour:[document valueForField:@"colour"] andCarYear:[document valueForField:@"caryear"]
                                            andCarDoors:[document valueForField:@"doors"] andCarSeat:[document valueForField:@"seat"] andCarWheels:[document valueForField:@"wheels"]
                                     andCarTankCapacity:[document valueForField:@"tankcapacity"] andCarHorsePower:[document valueForField:@"horsepower"] andCarModelName:[document valueForField:@"modelname"]];

                NSLog(@"Car name:%@", car.name);

                [self.myCars addObject:car];

            }
        }
    }];

}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return [self.myCars count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cellidentifier" forIndexPath:indexPath];

    // Configure the cell...'
    Vehicle *vehicle = [self.myCars objectAtIndex:indexPath.row];
    cell.textLabel.text = vehicle.name;

    return cell;
}



@end

Answer 1

在更改/更新数据源（在这种情况下为self.myCars之后，您需要手动重新加载数据，这意味着您需要在for循环之后添加[self.tableView reloadData];。如果仍然无法正常工作，则可能要检查self.myCars是否已初始化。

TableViewController不在表上显示信息

1 个答案: