ios - UITableViewCell 如何与其 UITableView 通信？

Question

我目前正在创建一个自定义 GridView ，这意味着我正在创建一个与 UITableView 有很多共同点的类。我想要做对的一件事是单元格和 GridView 的通信。

因此我想知道 TableView 单元格如何与其 TableView 对话。例如，单元格如何通知 TableView 它的删除按钮被点击并且单元格需要从 TableView 中删除？

有几种可能的情况，但我不确定 Apple 使用的是哪一种，因为 UITableView 或 UITableViewCell 的 header 揭示了这一点(或者我忽略了什么).

最终，目标是让单元格和 GridView 私下通信，即不公开任何公共(public)方法或协议(protocol)(如果可能的话)。

Answer 1

现在删除按钮可能不是一个很好的例子，因为 iOS 有一个内置方法，允许您删除行并通知您的数据源调用:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath

但是，为了便于理解，如果您想向 tableview 单元格添加一个按钮并让它执行标准 iOS 库中没有的操作，您可以在单元格中创建一个委托(delegate)并设置 tableview 的数据源文件作为代表。

基本上你会像这样子类化 UITableViewCell

MyCustomCell.h

@protocol MyCustomCellDelegate;
@interface MyCustomCell : UITableViewCell
@property (nonatomic, unsafe_unretained) id <MyCustomCellDelegate> delegate; //Holds a reference to our tableView class so we can call to it. 
@property (nonatomic, retain) NSIndexPath *indexPath; //Holds the indexPath of the cell so we know what cell had their delete button pressed
@end

/* Every class that has <MyCustomCellDelegate> in their .h must have these methods in them */
@protocol MyCustomCellDelegate <NSObject>
- (void)didTapDeleteButton:(MyCustomCell *)cell;
@end

MyCustomCell.m

@synthesize delegate = _delegate;
@synthesize indexPath = _indexPath;
- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier
{
    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) 
    {
    /* Create a button and make it call to a method in THIS class called deleteButtonTapped */
    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    button.frame = CGRectMake(5, 5, 25, 25);
    [button addTarget:self action:@selector(deleteButtonTapped:) forControlEvents:UIControlEventTouchUpInside];

    }
    return self;
}

/**
 * This is the method that is called when the button is clicked.
 * All it does is call to the delegate. (Whatever class we assigned to the 'delegate' property)
 */
- (void)deleteButtonTapped:(id)sender
{
    [self.delegate didTapDeleteButton:self];
}

您的 TableView 的数据源看起来像这样。

MyDataSource.h

/* We conform to the delegate. Which basically means "Hey you know those methods that we defined in that @protocol I've got them and you can safely call to them" */
@interface MyDataSource : UIViewController <MyCustomCellDelegate, UITableViewDelegate, UITableViewDataSource>
 @property (nonatomic,retain) NSArray *tableData;//We will pretend this is the table data
 @property (nonatomic,retain) UITableView *tableView;// We will pretend this is the tableview

@end

我的数据源.m

//We will pretend we synthesized and initialized the properties
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{
    MyCustomCell *cell = [tableView dequeueReusableCellWithIdentifier: @"MyCustomCell"];
    if (!cell) 
        cell = [[DownloadQueueCell alloc] initWithStyle: UITableViewCellStyleDefault reuseIdentifier: @"MyCustomCell"];
    cell.delegate = self;      // Make sure we set the cell delegate property to this file so that it calls to this file when the button is pressed.
    cell.indexPath = indexPath;// Set the indexPath for later use so we know what row had it's button pressed.
    return cell;
}


- (void)didTapDeleteButton:(MyCustomCell *)cell;
{

   // From here we would likely call to the apple API to Delete a row cleanly and animated
   // However, since this example is ignoring the fact that they exist
   // We will remove the object from the tableData array and reload the data
   [self.tableData removeObjectAtIndexPath:cell.indexPath];
   [self.tableView reloadData];

}

基本上，长话短说。对于您的 gridview，您只需创建一个委托(delegate)方法，告诉用户按下了某个按钮。