iOS TableView如何访问自定义单元格变量

Question

I have a table view

- (UITableViewCell *)tableView:(UITableView *)tableView 
         cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    **NSString *channelID = [object objectForKey:@"channelID"];**

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell==nil)
        cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle 
                                     reuseIdentifier:CellIdentifier];

}

I'm accessing a tableview cell like so:

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    for (NSIndexPath *path in [tableView indexPathsForVisibleRows]) {
        UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:path];
    }
    //I want to access cell.ChannelID //
}

How can I access the channelID variable? When the user stops scrolling I want to access the cells visible and a custom variable.

Thanks

Answer 1

If you want a custom UITableView cell, then you need to make a subclass of UITableView cell. From there, you need to declare a property on this custom cell for your object. Make sure that this property is declared publicly. From what I've seen in your code, it should probably be something like this.

@interface MyCustomCell : UITableViewCell

@property (strong, nonatomic) NSDictionary *myObject;

@end

From there, you'll want to import the header of the cell subclass into the implementation file that your table view delegate/datasource methods uses, and instead of referencing UITableViewCell inside cellForRowAtIndexPath: reference your subclass, then set a value to your newly added property.

- (MyCustomCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    MyCustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (!cell) {
        cell = [[MyCustomCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
    }

    NSString *channelID = [cell.myObject objectForKey:@"channelID"];

    [cell.textLabel setText:channelID];

    return cell;
}

Of course it should go without saying that you'll first need to provide logic to propagate this dictionary. Then as far as the scroll view delegate method goes, you have a similar problem. You can't access a custom object on the UITableViewCell base class. You once again need to reference your subclass. This can be easily done here with a simple cast.

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
    for (NSIndexPath *path in [tableView indexPathsForVisibleRows]) {
        MyCustomCell *cell = (MyCustomCell *)[self.tableView cellForRowAtIndexPath:path];

        NSString *channelID = [cell.myObject objectForKey:@"channelID"];
        //
    }
}

Answer 2

0x7fffffff answer works. You can also use this function and skip the null check.

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    MyCustomCell *cell = [tableView dequeueReusableCellWithIdentifier:@"CustomCell" forIndexPath:indexPath];

    NSString *channelID = [cell.myObject objectForKey:@"channelID"];

    [cell.textLabel setText:channelID];
}

But you must declare what a "CustomCell" is by registering it in viewDidLoad or you will get an exception:

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self.tableView registerClass:[CustomCell class] forCellReuseIdentifier:@"CustomCell"];
}

I like this better because it makes the dequeueReusableCellWithIdentifier: forIndexPath: is guaranteed to return a cell and makes cellForRowAtIndexPath a little cleaner. But either works just as well.

Answer 3

Are you sure channelID is a member of UITableViewCell? If you've subclasesed UITableViewCell and are using your own custom tableview cell, you want to use that class