ios - tableView为空时如何显示标签

Question

我想在 tableView 为空时显示一个标签。 我已经尝试过此页面上提出的其他解决方案，但没有一个对我有用。我想说“按添加按钮创建一个新类”之类的话。我的 TableviewController 是:

#import "ClasesTableViewController.h"
#import "ClasesTableViewCell.h"
#import "ViewController.h"

@interface ClasesTableViewController ()

@end

@implementation ClasesTableViewController

@synthesize clases;

- (NSManagedObjectContext *)managedObjectContext {
    NSManagedObjectContext *context  = nil;
    id delegate = [[UIApplication sharedApplication] delegate];
    if ([delegate performSelector:@selector(managedObjectContext)]) {
        context = [delegate managedObjectContext];
    }
    return context;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    [self.navigationItem setTitle:@"Clases"]; /*Cambia el titulo del navigation controller*/

    [self.navigationController.navigationBar setTitleTextAttributes:@{NSForegroundColorAttributeName : [UIColor whiteColor]}]; /*Cambia el color de las letras del navigation controller bar del menu principal*/

    [self.navigationController.navigationBar setBarTintColor:[UIColor colorWithRed:62/255.0f green:152/255.0f blue:73/255.0f alpha:1.0f]];

    self.TableView.tableFooterView = [[UIView alloc] init]; /*Esta linea hace que en la tabla solo aparezcan el numero de filas que tienes establecidas, es decir, que las vacias no aparezcan*/

    self.navigationController.navigationBar.tintColor = [UIColor whiteColor]; /*Cambia el color del boton de la izquierda*/

    UIBarButtonItem *infoBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"info_white48@2x.png"] style:UIBarButtonItemStylePlain target:self  action:@selector(infoAction)];

    self.navigationItem.rightBarButtonItems = [[NSArray alloc] initWithObjects: _AddBarButton, infoBarButtonItem, nil];


}


-(void)infoAction
{
    NSInteger clasesDadas = clases.count;

    NSString *inStr = [NSString stringWithFormat:@"\nClases dadas: %d", (int)clasesDadas];


    UIAlertView *alertatiempo = [[UIAlertView alloc] initWithTitle:@"Información" message:inStr delegate:self cancelButtonTitle:@"Aceptar" otherButtonTitles:nil];
    [alertatiempo show];

}



- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    if ([[segue identifier] isEqualToString:@"UpdateClase"]) {
        NSManagedObject *selectedClase = [clases objectAtIndex:[[self.TableView indexPathForSelectedRow] row]];
        ClasesViewController *destViewController = segue.destinationViewController;
        destViewController.clase = selectedClase;
        destViewController.numberOfClasses = clases.count;
    }
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    NSManagedObjectContext *moc = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Clases"];
    clases = [[moc executeFetchRequest:fetchRequest error:nil] mutableCopy];

    [self.tableView reloadData];

}

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

#pragma mark - Table view data source

- (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 clases.count;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"Cell";
    /*UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];*/
    ClasesTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];


    //Configure the cell
    NSManagedObject *clase = [clases objectAtIndex:indexPath.row];
    [cell.dateLabel setText:[NSString stringWithFormat:@"%@", /*countString,*/ [clase valueForKey:@"date"]/*, [clase valueForKey:@"date"]*/]];
    [cell.timeLabel setText:[clase valueForKey:@"time"]];
    [cell.paidLabel setText:[clase valueForKey:@"paid"]];
    cell.paidImage.image = [UIImage imageNamed:@" "];

    if ([cell.paidLabel.text isEqualToString:@"No"] || [cell.paidLabel.text isEqualToString:@"no"]) {
        cell.paidLabel.textColor = [UIColor redColor];
    }
    if ([cell.paidLabel.text isEqualToString:@"Si"] || [cell.paidLabel.text isEqualToString:@"si"]) {
        cell.paidLabel.textColor = [UIColor greenColor];
        cell.paidImage.image =[UIImage imageNamed:@"paid_green@2x.png"];
    }

    return cell;

}



 // Override to support conditional editing of the table view.
 - (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {

     // Return NO if you do not want the specified item to be editable.
     return YES;

 }


 // Override to support editing the table view.
 - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

     NSManagedObjectContext *context = [self managedObjectContext];

     if (editingStyle == UITableViewCellEditingStyleDelete) {
         // Delete the row from the data source
         [context deleteObject:[clases objectAtIndex:indexPath.row]];

         //invoke the "save" method to commit the change
         NSError *error = nil;
         if (![context save:&error]) {
              NSLog(@"Can't Delete! %@ %@", error, [error localizedDescription]);
             return;
         }

         //Remove clase from table view
         [clases removeObjectAtIndex:indexPath.row];
         [self.TableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];

     }
 }

@end

谁能帮帮我？非常感谢。

Answer 1

一个简单的解决方案是使用其他自定义 UITableViewCell 来显示空状态。

 - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section  
{
    return clases.count>0?clases.count:1;  //Return 1 if clases array is empty 
}

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{
  if(clases.count==0 && indexPath.row == 0)
  {
    //return a custom cell  with the label "Press the add button to create a new class"
  }
  else
  {
    //return an instance of ClasesTableViewCell as you was doing in your code which represents one class
  }
}