Question

我已阅读过每篇文章并多次尝试过每个解决方案，但无法获得正确的功能。

我有一个包含本地JSON文件数据的tableview。我需要用户能够：

选择多个单元格
在所选单元格上显示复选标记
将这些选择写入数组
取消选中时删除选择

5。当用户切换视图或离开并返回到tableview，关闭并重新打开应用程序等时，使用复选标记保存/保留选择

我已经设法让1-4工作，但我坚持＃5并且无法解决我的生活。我尽我所能地尝试过NSUserDefaults。任何帮助表示赞赏。以下是当前的代码。

另外，为什么我必须双击一个单元格才能取消选中它？

@interface FilterViewController () <UISearchResultsUpdating>

@property (nonatomic, strong) NSArray *IngredientsArray;
@property (nonatomic, strong) UISearchController *searchController;
@property (nonatomic, strong) NSMutableArray *searchResults;
@property (nonatomic, strong) NSMutableArray *selectedCell;
@property (nonatomic, strong) NSMutableArray *selectedIngredients;
//I added this property to keep track of the selected row
@property (strong,nonatomic) NSIndexPath *selectedPath;


@end

@implementation FilterViewController {
    NSArray *_locations;


}


- (void)viewDidLoad {


    [super viewDidLoad];

    self.selectedIngredients = [NSMutableArray array];
     self.selectedCell = [NSMutableArray array];
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    self.lastIndexPath = [defaults objectForKey:@"lastIndexPathUsed"];



    // Create a new JSONLoader with a local file URL
    JSONLoaderIngreds *jsonLoader = [[JSONLoaderIngreds alloc] init];
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"locations" withExtension:@"json"];

    // There's no transition in our storyboard to our search results tableview or navigation controller
    // so we'll have to grab it using the instantiateViewControllerWithIdentifier: method
    UINavigationController *searchResultsController = [[self storyboard] instantiateViewControllerWithIdentifier:@"FilterViewSearchResultsNavController"];

    // Our instance of UISearchController will use searchResults
    self.searchController = [[UISearchController alloc] initWithSearchResultsController:searchResultsController];

    // The searchcontroller's searchResultsUpdater property will contain our tableView.
    self.searchController.searchResultsUpdater = self;


    // create the searchBar programatically.
    self.searchController.searchBar.frame = CGRectMake(self.searchController.searchBar.frame.origin.x,
                                                       self.searchController.searchBar.frame.origin.y,
                                                       self.searchController.searchBar.frame.size.width, 44.0);

    self.tableView.tableHeaderView = self.searchController.searchBar;


    //Sets LocationsViewController as presenter for LocationDetailViewController after searxh results dsiplayed
    //and selected..  Required so searchbar doesn't show in detailsview after segue, and instead, default nav
    //controller back button displays.
    self.definesPresentationContext = true;





    // Load the data on a background queue...
    // As we are using a local file it's not really necessary, but if we were connecting to an online URL then we'd need it
    //NSString *ingreds = [dict objectForKey:@"ingredients"]
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        _locations = [jsonLoader ingredientsFromJSONFile:url];
        // Now that we have the data, reload the table data on the main UI thread
        [self.tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:YES];

        });

}

// Just before showing the LocationViewController, set the selected Location object
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
    LocationsViewController *vc = segue.destinationViewController;
    NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
    vc.location = [_locations objectAtIndex:indexPath.row];

}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

- (void)viewWillAppear:(BOOL)animated
{
    //I added this if clause to select the row that was last selected
    if (self.selectedPath != nil) {
        [self.tableView selectRowAtIndexPath:self.selectedPath animated:NO scrollPosition:UITableViewScrollPositionNone];
    }

}

#pragma mark - Table View Controller Methods

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

     self.selectedPath = indexPath;
    NSString *Ingredient = [_locations objectAtIndex:indexPath.row];
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    if([self isRowSelectedOnTableView:tableView atIndexPath:indexPath]){
        [self.selectedCell removeObject:indexPath];
        [self.selectedIngredients removeObject:Ingredient];
        cell.accessoryType = UITableViewCellAccessoryNone;
    } else {
        [self.selectedCell addObject:indexPath];
        [self.selectedIngredients addObject:Ingredient];
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }
    NSLog(@"***************Selected Ingredients**************** %@", self.selectedIngredients);
    NSUserDefaults *userdefaults = [NSUserDefaults standardUserDefaults];
    [userdefaults setObject:[NSString stringWithFormat:@"%ld",(long)indexPath.section] forKey:@"lastIndexPathUsed"];
    [userdefaults synchronize];


}

-(BOOL)isRowSelectedOnTableView:(UITableView *)tableView atIndexPath:(NSIndexPath *)indexPath
{
    return ([self.selectedCell containsObject:indexPath]) ? YES : NO;
}



- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *unifiedID = @"FilterCell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:unifiedID];

    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:unifiedID];
    }

    cell.textLabel.text = [_locations objectAtIndex:indexPath.row];
    cell.imageView.image = [UIImage imageNamed:@"ingredientsicon3232.png"];

    //if the indexPath was found among the selected ones, set the checkmark on the cell
    cell.accessoryType = ([self isRowSelectedOnTableView:tableView atIndexPath:indexPath]) ? UITableViewCellAccessoryCheckmark : UITableViewCellAccessoryNone;
    return cell;


}



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

更新

我设法根据建议更改了代码，使用下面的更新代码将选择保存到NSUserDefaults中的数组，但我仍然无法找出保存/调用复选标记所需的cellForRowAtIndexPath代码。 / p>

我如何编码cellForRowAtIndexPath来调用复选标记？

使用以下代码将选择保存到数组：

ViewDidLoad代码：

_selections = [NSMutableArray arrayWithArray:(NSArray *)[[NSUserDefaults standardUserDefaults] objectForKey:@"selections"]];
    if(_selections == nil){
        _selections = [[NSMutableArray alloc] init];
    }

didSelectRowAtIndexPath代码：

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];

    {
    if ([_selections containsObject: cell.textLabel.text] == NO){
        [_selections addObject:cell.textLabel.text];
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    } else {
        [_selections removeObject:cell.textLabel.text];
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
    NSLog(@"***************Selected Ingredients**************** %@", _selections);
    NSUserDefaults *userdefaults = [NSUserDefaults standardUserDefaults];

    [userdefaults setObject:_selections forKey:@"selections"];
    [userdefaults synchronize];
    NSLog(@"-------------NSUserDefaults------------%@", [[NSUserDefaults standardUserDefaults] dictionaryRepresentation])

}

Answer 1

您的解决方案非常简单。

首先，您需要将一系列选定的索引路径保存到用户默认对象，而不是仅保留最后选择的路径。
每当用户选择或取消选择一行时。添加和删除同一阵列中的对象并将其保存回用户默认值。
在ComponentDidMount中，检查您的索引路径是否存在于用户默认值中保存的阵列中。如果存在，请选中带有复选标记的行，否则保持原样。

希望这会有所帮助。

Answer 2

我认为不是使用那些indexPath，而是建议您直接使用数据本身，添加Bool属性以指示Ingredient类中的选择，然后保存CoreData/Realm/NSUserDefault中的整个数组，由于您的数据可以更改，导致您保存的选择indexPath不再正确，因此更正确

储蓄，保留，和检索数组

2 个答案: