【发布时间】：2016-08-11 02:16:18
【问题描述】：
我已阅读每篇文章并多次尝试每种解决方案，但无法获得正确的功能。
我有一个表格视图，其中包含来自本地 JSON 文件的数据。我需要用户能够：
- 选择多个单元格
- 在选定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表格视图、关闭和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，但我被困在 #5 上，无法终生解决这个问题。我已经尽我所能尝试了 NSUserDefaults。任何帮助表示赞赏。以下是当前代码。
另外，为什么我必须双击一个单元格来取消选中它？
@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：
我设法按照建议更改了代码，使用下面的更新代码将选择保存到 NSUserDefaults 中的数组，但我仍然无法弄清楚保存/调用复选标记所需的 cellForRowAtIndexPath 代码。
如何编写 cellForRowAtIndexPath 代码来调用复选标记？
使用此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])
}
【问题讨论】：
标签： ios objective-c arrays uitableview nsuserdefaults