在具有 2 个数据源的一个 TableView 中选择不同的单元格

Question

在一个视图 controller 上，我有一个UITableView和一个UISegmentedControl在它的顶部。 表视图由 NSArray 填充，该 NSArray 从几种不同的方式之一收集文件。 0 段从 2 个文件夹中提取所有 PDF。 1 段从文件名末尾包含“Kids.pdf”的文件夹中提取所有 PDF。 我想要做的是允许用户创建他们喜欢的歌曲列表并保存。 当段更改时，我成功地显示了我想要的内容，但问题是复选标记仍然存在。 所以，如果我 select 从第一个段的顶行开始，当我 go 到另一个段时，它仍然显示一个也被选中。 我 go 如何解决这个问题，以便在每个段之间来回切换将保留用户实际选择的复选标记？

- (void)viewWillAppear:(BOOL)animated {
    
   
    self.title = @"Choose YourSongs";
    if (filterSongs.selectedSegmentIndex == 0) {
    NSBundle *bundle = [NSBundle mainBundle];
    
    self.files  = [bundle pathsForResourcesOfType:@"pdf" inDirectory:@"thepdfpowerpoints"];
    NSString *documentsDirectoryPath = [self.files objectAtIndex:thepath.row];
    self.filenames = [[documentsDirectoryPath lastPathComponent] stringByDeletingPathExtension];
    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
       NSString *documentsDirectory = [paths objectAtIndex:0];
    NSArray *thefirstNewArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsDirectory error:NULL];
    NSArray *theNewArray = [thefirstNewArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self ENDSWITH '.pdf'"]];

   
    NSMutableArray *names = [NSMutableArray arrayWithCapacity:[self.files count] + [theNewArray count]];
    for (NSString *path in self.files) {
        [names addObject:[[path lastPathComponent] stringByDeletingPathExtension]];
    }
    for (NSString *pathagain in theNewArray) {
        [names addObject:[[pathagain lastPathComponent] stringByDeletingPathExtension]];
    }
    //self.files = names;
    self.files = [names sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
    NSLog(@"FILESLOAD%@", self.files);

     self.tableView.delegate = self;
       self.tableView.dataSource = self;
    }
    else {
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
           NSString *documentsDirectory = [paths objectAtIndex:0];
        NSArray *thefirstNewArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsDirectory error:NULL];
        NSArray *theNewArray = [thefirstNewArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self ENDSWITH 'Kids.pdf'"]];

       
        NSMutableArray *names = [NSMutableArray arrayWithCapacity:[theNewArray count]];
        for (NSString *path in self.files) {
            [names addObject:[[path lastPathComponent] stringByDeletingPathExtension]];
        }
        for (NSString *pathagain in theNewArray) {
            [names addObject:[[pathagain lastPathComponent] stringByDeletingPathExtension]];
        }
        //self.files = names;
        self.files = [names sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
        NSLog(@"FILESLOAD%@", self.files);

         self.tableView.delegate = self;
           self.tableView.dataSource = self;
    }
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
        NSString *selectedCountry = [self.files objectAtIndex:indexPath.row];
    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
       NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *pdfPath = [[documentsDirectory stringByAppendingPathComponent:selectedCountry] stringByAppendingString:@".pdf"];
    if  ([[NSFileManager defaultManager] fileExistsAtPath: pdfPath]) {
        //NSLog(@"%@", selectedCountry);
        UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
        
        NSString *addThis = [[pdfPath lastPathComponent] stringByDeletingPathExtension];
        NSLog(@"%@", addThis);
      
        values[indexPath.row] = !values[indexPath.row];
        if (self.chosen == nil) {
            self.chosen = [[NSMutableArray alloc] init];
        }
        if (values[indexPath.row]) {
            newCell.accessoryType = UITableViewCellAccessoryCheckmark;
            [self.chosen addObject:addThis];

        } else {
            newCell.accessoryType = UITableViewCellAccessoryNone;
            [self.chosen removeObject:addThis];

        }
    }
    
    
    else {
    
    
        NSString *Documents = [[NSBundle mainBundle] pathForResource:selectedCountry ofType:@"pdf" inDirectory:@"thepdfpowerpoints"];
        //NSLog(@"%@", selectedCountry);
        UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
        
        NSString *addThis = [[Documents lastPathComponent] stringByDeletingPathExtension];
        NSLog(@"%@", addThis);
      
        values[indexPath.row] = !values[indexPath.row];
        if (self.chosen == nil) {
            self.chosen = [[NSMutableArray alloc] init];
        }
        if (values[indexPath.row]) {
            newCell.accessoryType = UITableViewCellAccessoryCheckmark;
            [self.chosen addObject:addThis];

        } else {
            newCell.accessoryType = UITableViewCellAccessoryNone;
            [self.chosen removeObject:addThis];

        }
    }
        [self.tableView deselectRowAtIndexPath:indexPath animated:YES];
       
    
}

最后是段的代码。

-(IBAction) changeSegment {
    

    if (filterSongs.selectedSegmentIndex == 0) {
    NSBundle *bundle = [NSBundle mainBundle];
    
    self.files  = [bundle pathsForResourcesOfType:@"pdf" inDirectory:@"thepdfpowerpoints"];
    NSString *documentsDirectoryPath = [self.files objectAtIndex:thepath.row];
    self.filenames = [[documentsDirectoryPath lastPathComponent] stringByDeletingPathExtension];
    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
       NSString *documentsDirectory = [paths objectAtIndex:0];
    NSArray *thefirstNewArray = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsDirectory error:NULL];
    NSArray *theNewArray = [thefirstNewArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self ENDSWITH '.pdf'"]];

   
    NSMutableArray *names = [NSMutableArray arrayWithCapacity:[self.files count] + [theNewArray count]];
    for (NSString *path in self.files) {
        [names addObject:[[path lastPathComponent] stringByDeletingPathExtension]];
    }
    for (NSString *pathagain in theNewArray) {
        [names addObject:[[pathagain lastPathComponent] stringByDeletingPathExtension]];
    }
    //self.files = names;
    self.files = [names sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

     self.tableView.delegate = self;
       self.tableView.dataSource = self;
        [self.tableView reloadData];

    }
    else {
        self.files = nil;
        NSArray *paths2 = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
           NSString *documentsDirectory2 = [paths2 objectAtIndex:0];
        NSArray *thefirstNewArray2 = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsDirectory2 error:NULL];
        NSArray *theNewArray2 = [thefirstNewArray2 filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self ENDSWITH 'Kids.pdf'"]];
        NSLog(@"Kids newArray %@", thefirstNewArray2);
       
        NSMutableArray *names2 = [NSMutableArray arrayWithCapacity:[theNewArray2 count]];
       
        for (NSString *pathagain2 in theNewArray2) {
            [names2 addObject:[[pathagain2 lastPathComponent] stringByDeletingPathExtension]];
        }
        //self.files = names;
        self.files = [names2 sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

         self.tableView.delegate = self;
           self.tableView.dataSource = self;
        [self.tableView reloadData];
    }
 
}

Answer 1

它非常简单。 当您更改段选择（更改数据源）时，选中标记的单元格将被重用，因此它显示最新的 state 的单元格。您需要重置 cellForRowAtIndexPath 方法中的所有状态：

 (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
     //...
      if (values[indexPath.row]) {
            cell.accessoryType = UITableViewCellAccessoryCheckmark;
        } else {
            cell.accessoryType = UITableViewCellAccessoryNone;
        }
     return cell;
 }

一般来说，记住。 如果单元格中有if ，则还应该有else case，否则会出现重用问题。