多个复选标记来自

Question

我正在关注的教程：http://www.appcoda.com/ios-programming-tutorial-create-a-simple-table-view-app/

我创建了一个包含 16 个单元格的表格视图。当我选择一行时，它会在上面显示复选标记。

但是当我滚动表格视图时，列表下方的另一个单元格上还会显示一个复选标记。这对选定的任何单元格重复。

    #import "FlightChecklistViewController.h"

    @interface FlightChecklistViewController ()

    @end

    @implementation FlightChecklistViewController

{
    NSArray *tableData;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    // Initialize table data
    tableData = [NSArray arrayWithObjects:@"Egg Benedict", @"Mushroom Risotto", @"Full Breakfast", @"Hamburger", @"Ham and Egg Sandwich", @"Creme Brelee", @"White Chocolate Donut", @"Starbucks Coffee", @"Vegetable Curry", @"Instant Noodle with Egg", @"Noodle with BBQ Pork", @"Japanese Noodle with Pork", @"Green Tea", @"Thai Shrimp Cake", @"Angry Birds Cake", @"Ham and Cheese Panini", nil];

}

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

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *simpleTableIdentifier = @"SimpleTableItem";

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];

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

    cell.textLabel.text = [tableData objectAtIndex:indexPath.row];
    return cell;
}

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

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UIAlertView *messageAlert = [[UIAlertView alloc]
                                    initWithTitle:@"Row Selected" message:@"You've selected a row" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

    // Display Alert Message
    [messageAlert show];

    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    cell.accessoryType = UITableViewCellAccessoryCheckmark;

    [tableView deselectRowAtIndexPath:indexPath animated:YES];

}

@end

有什么建议吗？

Answer 1

您需要以某种方式存储有关所选行索引路径的信息。 并根据它填充您的单元格。

#import "ViewController.h"

@interface ViewController ()
@property (nonatomic, strong) NSMutableArray *selectedCells;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.selectedCells = [NSMutableArray array];
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 100;
}

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *unifiedID = @"aCellID";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:unifiedID];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:unifiedID];
    }

    cell.textLabel.text = [NSString stringWithFormat:@"%u", indexPath.row];

    //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;

}

//if a row gets selected, toggle checkmark    
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    if([self isRowSelectedOnTableView:tableView atIndexPath:indexPath]){
        [self.selectedCells removeObject:indexPath];
        cell.accessoryType = UITableViewCellAccessoryNone;
    } else {
        [self.selectedCells addObject:indexPath];
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }
}

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

@end

你可以在github找到完整的示例代码

Answer 2

问题是细胞被重复使用。因此，如果您将复选标记附件视图添加到更上方的单元格，它将在该单元格被更下方重复使用时再次出现。添加/删除复选标记时，您应该将哪些已复选标记保存在与表格行相关的某个位置的数组中。然后，当您给表格视图一个新单元格时，您可以确定它是否需要复选标记并进行设置。

Answer 3

我最近在使用我的一个应用时遇到了同样的问题，我通过这样做解决了这个问题：

@property (nonatomic, strong) NSArray *list;

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.list = [[NSArray alloc] initWithObjects:@"foo", @"bar", nil];
}

- (NSString *)SettingsPlist
{
    NSString *paths = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSString *PlistPath = [paths stringByAppendingPathComponent:@"Settings.plist"];
    return PlistPath;
}

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

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *contentForThisRow = [[self list] objectAtIndex:[indexPath row]];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];

    if(cell == nil)
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"Cell"];
    }

    NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:[self SettingsPlist]];

    NSString *row = [NSString stringWithFormat:@"%d",indexPath.row];

    if([[dict objectForKey:row]isEqualToString:@"0"])
    {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
    else
    {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }

    [[cell textLabel] setText:contentForThisRow];

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSMutableDictionary *plist = [NSMutableDictionary dictionaryWithContentsOfFile:[self SettingsPlist]];

    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];

    NSString *row = [NSString stringWithFormat:@"%d",indexPath.row];

    if(cell.accessoryType == UITableViewCellAccessoryNone)
    {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
        NSString *on = @"1";
        [plist setObject:on forKey:row];
        [plist writeToFile:[self SettingsPlist] atomically:YES];
    }
    else if(cell.accessoryType == UITableViewCellAccessoryCheckmark)
    {
        cell.accessoryType = UITableViewCellAccessoryNone;
        NSString *off = @"0";
        [plist setObject:off forKey:row];
        [plist writeToFile:[self SettingsPlist] atomically:YES];
    }
    [tableView deselectRowAtIndexPath:indexPath animated:YES];
}