cellForRowAtIndexPath返回null但确实需要类似的方法

Question

我有一个UITableView在我的UITableViewController(笑,很明显),但我需要的内部定索引处获得细胞- (void)viewWillAppear:(BOOL)animated的方法.

现在,我的单元格是静态的,我在界面构建器中创建它们.如果我打电话

UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:previously_selected_cell.integerValue inSection:0]];

它为单元格返回null.我在1个部分中只有3个静态单元.我尝试了0和1节,并且都返回null.

目前我已经删除了该- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath方法,因为如果我添加它,它将清除UITableView所有静态单元格.

有没有我可以调用的方法- (void)viewWillAppear:(BOOL)animated将返回给定索引处的单元格？

提前致谢!

编辑:我检查了这个计算器的问题,但我使用静态细胞无的cellForRowAtIndexPath,这样的问题没有帮助.:(

EDIT2:我正在尝试在视图加载时设置单元格的附件类型.但仅在某个单元格上,该单元格是用户在退出应用程序之前选择的单元格.

#import "AutoSyncSettings.h"
#import "CDFetchController.h"


@implementation AutoSyncSettings

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

#pragma mark - View lifecycle

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

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (void)viewWillAppear:(BOOL)animated
{
    CDFetchController *cdfc = [[CDFetchController alloc] init];
    NSFetchedResultsController *results = [cdfc getFetchedResultsControllerWithEntityName:@"SETTINGS"];
    NSArray *objects = [results fetchedObjects];
    NSNumber *sync_setting;

    if(objects.count > 0)
    {     
        NSManagedObject *object = [objects objectAtIndex:0];
        sync_setting = [object valueForKey:@"wifi_setting"];

        NSLog(@"(Settings)sync_setting: %@",sync_setting);
    NSLog(@"(Settings)sync_setting int value: %i",sync_setting.integerValue);
    NSLog(@"(Settings)TableView: %@",self.tableView);

//cell is null, even after this.
    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:wifi_settings.integerValue inSection:0]];
    cell.accessoryType = UITableViewCellAccessoryCheckmark;
//cell is still null. WHY OH WHY? :(

        objects = nil;
    }

    cdfc = nil;
    results = nil;
    objects = nil;
    sync_setting = nil;

    [super viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated
{
    [super viewDidDisappear:animated];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

#pragma mark - Table view data source

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    return NO;
}

- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
    return NO;
}

#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    for (int i = 0; i < [tableView numberOfRowsInSection:indexPath.section]; i++)
    {
        if([[tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:indexPath.section]] accessoryType] == UITableViewCellAccessoryCheckmark)
        {
            [tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:indexPath.section]].accessoryType = UITableViewCellAccessoryNone;
        }
    }

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

    CDFetchController *cdfc = [[CDFetchController alloc] init];
    NSFetchedResultsController *results = [cdfc getFetchedResultsControllerWithEntityName:@"SETTINGS"];
    NSManagedObjectContext *context = [results managedObjectContext];
    NSArray *objects = [results fetchedObjects];

    if(objects.count > 0)
    {

        NSManagedObject *object = [objects objectAtIndex:0];

        NSNumber *sync_setting = [NSNumber numberWithInt:indexPath.row];
        [object setValue:sync_setting forKey:@"sync_interval"];
        [object setValue:[NSNumber numberWithInt:0] forKey:@"id"];

        [ErrorHandler saveMoc:context];
    }
    else
    {
        //INSERT NEW OBJECT
        NSManagedObject *object = [NSEntityDescription insertNewObjectForEntityForName:@"SETTINGS" inManagedObjectContext:context];

        NSNumber *sync_setting = [NSNumber numberWithInt:indexPath.row];
        [object setValue:sync_setting forKey:@"sync_interval"];
        [object setValue:[NSNumber numberWithInt:0] forKey:@"id"];

        [ErrorHandler saveMoc:context];
    }
}

@end

Answer 1

我有一个项目正是这样做,它完美地运作.但是,除非在尝试以这种方式访问​​单元格之前调用,否则它不起作用[super viewWillAppear:animated].

基本实现可能会从故事板中加载到单元格中.