How can I subclass a UITableView?

Question

I want to subclass a UITableView as I want to create a reusable table view component in my application.

The idea is instead of using a delegate for say cellForRowA

Answer 1

MyTableView.h

// MyTableView.h

// This overrides the UITableViewDataSource with your own so you can add any methods   you would like.
@protocol MyTableViewDataSource 

@required
// This is where you put methods that are required for your custom table to work (optional)
- (int)myRequiredMethod;

@optional
// This is where you put methods that are optional, like settings (optional)

@end

// This overrides the UITableViewDelegate with your own so you can add any methods you would like.
@protocol MyTableViewDelegate 

@required
// This is where you put methods that are required for your custom table to work (optional)

@optional
// This is where you put methods that are optional, like settings (optional)

@end

// Make sure you add UITableViewDelegate and UITableViewDataSource implementations.
@interface MyTableView : UITableView  {

    // Your customer datasource and delegate.
    id  myDataSource;
    id  myDelegate;
}

@end

MyTableView.m

// MyTableView.m

#import "MyTableView.h"

@implementation MyTableView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code

        // This is how you can use your custom method.
        int i = [myDataSource myRequiredMethod];
    }
    return self;
}

- (void)awakeFromNib {
    // This assigns the delegate and datasource you assigned to File's Owner in your xib to your custom methods
    myDataSource = (id)self.dataSource;
    myDelegate = (id)self.delegate;
    self.delegate = self;
    self.dataSource = self;
}

// This is an example of how to override an existing UITableView method.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    // This calls the method implemented in your ViewController. See Below.
    NSInteger rows = [myDataSource tableView:tableView numberOfRowsInSection:section];

    return rows;
}

@end

MyViewController.h

// MyViewController.h

#import "MyTableView.h"

// Use MyTableViewDataSource and MyTableViewDelegate instead of UITableViewDataSource and UITableViewDelegate
@interface MyViewController : UIViewController  {

@end

MyViewController.m

// MyViewController.m

#import "MyViewController.h"

@interface MyViewController ()

@end

@implementation MyViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

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

// This method will be overridden by myTableViewDataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return 1;
}

- (int)myRequiredMethod {
    return 2;
}

Subclassing is a great way to make reusable custom UI elements.