Objective-C iOS Development for Legacy & Enterprise Apps · 课时

表格视图与集合视图

实现和自定义 UITableView 与 UICollectionView，用于显示动态内容列表和网格。

表格视图与集合视图 是 CoddyKit 上的免费 Objective-C iOS Development for Legacy & Enterprise Apps 课时。这是第 3 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Objective-C iOS Development for Legacy & Enterprise Apps 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Objective-C iOS Development for Legacy & Enterprise Apps 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Meet UITableView

Welcome to lists! UITableView is a fundamental UIKit component used to display scrollable lists of data, commonly seen in apps for settings, contacts, or news feeds.

It's optimized for efficiency, only rendering the cells visible on screen, which makes it perfect for long lists without performance issues.

Data & Behavior for Tables

To work with a UITableView, you primarily interact with two protocols:

UITableViewDataSource: This tells the table view what data to display (e.g., number of rows, content for each cell).
UITableViewDelegate: This handles how the table view behaves (e.g., row selection, height of rows, custom actions).

Your view controller typically conforms to both.

Your First Table View

Let's create a basic UITableView programmatically. This code snippet assumes it's within a UIViewController subclass that is set as the app's root view controller.

We add the table view to our controller's main view, making it fill the screen.

#import <UIKit/UIKit.h>

@interface MyTableViewController : UIViewController
@end

@implementation MyTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    // Create a UITableView filling the view
    UITableView *tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
    tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    
    // We'll set the data source and delegate in next steps
    // tableView.dataSource = self; 
    
    [self.view addSubview:tableView];
}
@end

Populating Your Table

To display data, our MyTableViewController needs to conform to the UITableViewDataSource protocol. This means implementing two key methods:

numberOfRowsInSection: Tells the table how many rows to expect.
cellForRowAtIndexPath: Provides the UITableViewCell for each row.

We also register a basic UITableViewCell for reuse.

#import <UIKit/UIKit.h>

@interface MyTableViewController : UIViewController <UITableViewDataSource>
@property (nonatomic, strong) NSArray *dataItems;
@property (nonatomic, strong) UITableView *tableView;
@end

@implementation MyTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.dataItems = @[@"Apple", @"Banana", @"Cherry", @"Date"];
    
    self.tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
    self.tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    self.tableView.dataSource = self; // Set self as data source
    
    // Register a basic UITableViewCell class for reuse
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"Cell"];
    
    [self.view addSubview:self.tableView];
}

#pragma mark - UITableViewDataSource methods

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return self.dataItems.count; // Number of items in our data array
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    // Dequeue (reuse) or create a cell
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell" forIndexPath:indexPath];
    cell.textLabel.text = self.dataItems[indexPath.row]; // Set cell's text
    return cell;
}
@end

Making Cells Unique

UITableViewCell is the view that displays content for each row. You can customize its appearance by:

Using built-in styles (e.g., UITableViewCellStyleSubtitle).
Adding subviews directly to cell.contentView.
Creating a custom subclass of UITableViewCell for complex layouts.

Always reuse cells with dequeueReusableCellWithIdentifier: for performance.

#import <UIKit/UIKit.h>

@interface MyTableViewController : UIViewController <UITableViewDataSource>
@property (nonatomic, strong) NSArray *dataItems;
@property (nonatomic, strong) UITableView *tableView;
@end

@implementation MyTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.dataItems = @[@"Apple", @"Banana", @"Cherry", @"Date"];
    
    self.tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];
    self.tableView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    self.tableView.dataSource = self;
    // Registering a cell class (we'll use the default for demo)
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"CustomCell"];
    
    [self.view addSubview:self.tableView];
}

#pragma mark - UITableViewDataSource methods

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return self.dataItems.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    // Dequeue a cell, using UITableViewCellStyleSubtitle for more options
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"CustomCell" forIndexPath:indexPath];
    
    cell.textLabel.text = self.dataItems[indexPath.row];
    cell.detailTextLabel.text = [NSString stringWithFormat:@"Item #%ld", (long)indexPath.row + 1];
    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; // Add an arrow
    
    return cell;
}
@end

Flexible Grids: UICollectionView

While UITableView excels at vertical lists, UICollectionView offers much more flexibility for displaying content in customizable layouts, like grids, carousels, or complex dashboards.

It's ideal when you need to arrange items in non-linear or highly visual ways, such as photo galleries, product catalogs, or tag clouds.

Collection View's Data & Flow

Similar to table views, collection views rely on a UICollectionViewDataSource to provide data and a UICollectionViewDelegate for interaction.

A key difference is the UICollectionViewLayout. This object defines how items are arranged (e.g., grid, flow, custom). The most common is UICollectionViewFlowLayout for grid-like structures.

Building Your First Collection

Let's set up a basic UICollectionView. We'll also need to provide a UICollectionViewLayout to tell it how to arrange its items.

UICollectionViewFlowLayout is a good starting point for simple grids, allowing you to define item sizes and spacing.

#import <UIKit/UIKit.h>

@interface MyCollectionViewController : UIViewController
@property (nonatomic, strong) UICollectionView *collectionView;
@end

@implementation MyCollectionViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    // Create a flow layout for grid arrangement
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    layout.itemSize = CGSizeMake(100, 100); // Size for each item
    layout.minimumInteritemSpacing = 10;    // Min spacing between items in a row
    layout.minimumLineSpacing = 10;         // Min spacing between rows
    
    self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
    self.collectionView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    self.collectionView.backgroundColor = [UIColor systemGroupedBackgroundColor]; // For contrast
    
    // We'll set the data source in the next step
    // self.collectionView.dataSource = self;
    
    [self.view addSubview:self.collectionView];
}
@end

Populating Your Collection

To display items, our MyCollectionViewController needs to conform to UICollectionViewDataSource. It's similar to UITableViewDataSource:

numberOfItemsInSection: Specifies the number of items.
cellForItemAtIndexPath: Provides the UICollectionViewCell for each item.

Remember to register a cell class or nib before dequeuing!

#import <UIKit/UIKit.h>

@interface MyCollectionViewController : UIViewController <UICollectionViewDataSource>
@property (nonatomic, strong) NSArray *dataItems;
@property (nonatomic, strong) UICollectionView *collectionView;
@end

@implementation MyCollectionViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.dataItems = @[@"Red", @"Green", @"Blue", @"Yellow", @"Orange", @"Purple"];
    
    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];
    layout.itemSize = CGSizeMake(80, 80);
    layout.minimumInteritemSpacing = 5;
    layout.minimumLineSpacing = 5;
    layout.sectionInset = UIEdgeInsetsMake(5, 5, 5, 5); // Padding around sections
    
    self.collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:layout];
    self.collectionView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    self.collectionView.backgroundColor = [UIColor systemGroupedBackgroundColor];
    self.collectionView.dataSource = self; // Set self as data source
    
    // Register a basic UICollectionViewCell class
    [self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"CollectionCell"];
    
    [self.view addSubview:self.collectionView];
}

#pragma mark - UICollectionViewDataSource methods

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return self.dataItems.count;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"CollectionCell" forIndexPath:indexPath];
    
    // Simple customization: set background color based on item
    NSArray *colors = @[[UIColor redColor], [UIColor greenColor], [UIColor blueColor], [UIColor yellowColor],
                            [UIColor orangeColor], [UIColor purpleColor]];
    cell.backgroundColor = colors[indexPath.item % colors.count];
    
    // Add a label to the cell for text (optional)
    UILabel *label = (UILabel *)[cell.contentView viewWithTag:100];
    if (!label) {
        label = [[UILabel alloc] initWithFrame:cell.contentView.bounds];
        label.tag = 100;
        label.textAlignment = NSTextAlignmentCenter;
        label.textColor = [UIColor whiteColor];
        label.font = [UIFont systemFontOfSize:14];
        [cell.contentView addSubview:label];
    }
    label.text = self.dataItems[indexPath.item];
    
    return cell;
}
@end

Table vs. Collection

Both UITableView and UICollectionView display lists of data, but they have different strengths.

Which of the following is a primary advantage of using UICollectionView over UITableView?

Recap: Lists & Grids

We explored UITableView for displaying efficient vertical lists and UICollectionView for highly customizable grid and non-linear layouts.

Both use Data Source and Delegate protocols to manage content and behavior.
UITableView is simpler for standard, single-column lists.
UICollectionView uses a UICollectionViewLayout for powerful and custom visual arrangements.

Mastering these components is crucial for building dynamic and engaging iOS user interfaces.

常见问题解答

「表格视图与集合视图」课时是免费的吗？

是的 — 「表格视图与集合视图」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Objective-C iOS Development for Legacy & Enterprise Apps 课程的其余内容，请升级到 CoddyKit PRO。 Objective-C iOS Development for Legacy & Enterprise Apps 课程共包含 4 节课。

「表格视图与集合视图」这节课中我会学到什么？

实现和自定义 UITableView 与 UICollectionView，用于显示动态内容列表和网格。你通过在浏览器中直接运行的动手代码来练习 Objective-C iOS Development for Legacy & Enterprise Apps，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Objective-C iOS Development for Legacy & Enterprise Apps 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Objective-C iOS Development for Legacy & Enterprise Apps 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 3 节课，共 4 节。

「表格视图与集合视图」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

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