重载视图后如何保存tableView单元格的复选标记使用NSUserDefaults？

Question

我是ios开发的新手,我在一个单元格中使用了checkmark UITableView.

我想在NSUserDefaults数据库中存储已检查的单元格,当我重新加载应用程序时,将显示之前选中的已检查单元格,我尝试不同的方式,但仍未能实现它.

有人可以帮帮我吗？我将非常感激.对不起,我的英语不好.

我的代码如下:

#import "FirstRowSubview.h"

@interface FirstRowSubview ()

@end

@implementation FirstRowSubview

@synthesize array = _array;
@synthesize lastIndexPath = _lastIndexPath;


- (void)viewDidLoad
{
    [super viewDidLoad];
    NSMutableArray *list = [[NSMutableArray alloc] initWithObjects:@"ffgfgh", @"564654", @"56548", @"fgmjfgmf", @"ggkdj", nil];
    self.array = list;
    [list release];

}

- (void)viewDidUnload
{
    [super viewDidUnload];
    self.array = nil;
}


#pragma mark -
#pragma mark - TableView Datasource Methods

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

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *subviewCells = @"Cells";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:subviewCells];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:subviewCells];
    }
    NSUInteger oldRow = [_lastIndexPath row];
    cell.accessoryType = (indexPath.row == oldRow && _lastIndexPath != nil) ?
    UITableViewCellAccessoryCheckmark : UITableViewCellAccessoryNone;
    cell.textLabel.text = [_array objectAtIndex:indexPath.row];

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:[NSNumber numberWithInt:_lastIndexPath.row] forKey:@"lastIndexPath"];
    [defaults synchronize];



    return cell;
 }

#pragma mark -
#pragma mark - TableView Delegate Methods

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    int newRow = [indexPath row];
    int oldRow = (_lastIndexPath != nil) ? [_lastIndexPath row] : -1;

    if (newRow != oldRow) {
        UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
        newCell.accessoryType = UITableViewCellAccessoryCheckmark;

        UITableViewCell *oldCell = [tableView cellForRowAtIndexPath:_lastIndexPath];
        oldCell.accessoryType = UITableViewCellAccessoryNone;

        [indexPath retain];
        [_lastIndexPath release];
        _lastIndexPath = indexPath;


        [tableView deselectRowAtIndexPath:indexPath animated:YES];


    }

}

Answer 1

可以很容易地存储和检索已检查的单元格信息NSUserDefaults.

NSUserDefaults可以存储Key/Value对的数据中间件.在这里,你的情况的值可以是布尔和关键可能的组合NSString:indexpath.row从UITableView.

你可以做一个像,

- (NSString *)getKeyForIndex:(int)index
{
    return [NSString stringWithFormat:@"KEY%d",index];
}

- (BOOL) getCheckedForIndex:(int)index
{                     
    if([[[NSUserDefaults standardUserDefaults] valueForKey:[self getKeyForIndex:index]] boolValue]==YES) 
    { 
        return YES;
    }
    else 
    { 
        return NO; 
    }
}

- (void) checkedCellAtIndex:(int)index
{
    BOOL boolChecked = [self getCheckedForIndex:index];

    [[NSUserDefaults standardUserDefaults] setValue:[NSNumber numberWithBool:!boolChecked] forKey:[self getKeyForIndex:index]];
    [[NSUserDefaults standardUserDefaults] synchronize];
}


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


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    //Here, you can check for previously checked cells like

    static NSString *subviewCells = @"Cells";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:subviewCells];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:subviewCells];
    }

    cell.textLabel.text = [_array objectAtIndex:indexPath.row];

    if([self getCheckedForIndex:indexPath.row]==YES)
    {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }
    else
    {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }

    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [tableView deselectRowAtIndexPath:indexPath animated:NO];

    //Use checkedCellAtIndex for check or uncheck cell
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];

    [self checkedCellAtIndex:indexPath.row];

    if([self getCheckedForIndex:indexPath.row]==YES)
    {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }
    else
    {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
}

PS请注意,如果您的数据顺序NSArray始终保持相同的顺序,此方法仅有用且建议.其他然后NSUserDefaults,你象是选项SQLite Database或plist file或任何其他的选择!谢谢 :)