Question

I have a UIViewController that I want to use to implement the methods of UITableViewDataSource on. I have this header, FriendsController.h:

#import <UIKit/UIKit.h>
@interface FriendsController : UIViewController <UITableViewDataSource>
@end

Edit: now updated the @interface declaration to:

@interface FriendsController : UIViewController <UITableViewDataSource, UITableViewDelegate>

and this implementation, FriendsController.m:

#import "FriendsController.h"

@implementation FriendsController

- (NSInteger)tableView:(UITableView *)tableView 
numberOfRowsInSection:(NSInteger)section
{
  // Return the number of rows in the section.
  NSLog(@"CALLED .numberOfRowsInSection()");
  return 1;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
  NSLog(@"CALLED cellForRowAtIndexPath()");
  UITableViewCell *cell = [tableView
                             dequeueReusableCellWithIdentifier:@"FriendCell"];
  cell.textLabel.text = @"Testing label";
  return cell;
}
@end

When run this gives me a ‘-[UIView tableView:numberOfRowsInSection:]: unrecognized selector sent to instance 0x81734d0‘. Can anyone see if there is something wrong with my implementation/declaration of .numberOfRowsInSection()?

Edit: I’ve added a technique for method listing from here and run the view ‘unconnected’, it outputs the following list:

[<timestamp etc>] Method no #0: tableView:numberOfRowsInSection:
[<timestamp etc>] Method no #1: tableView:cellForRowAtIndexPath:
[<timestamp etc>] Method no #2: numberOfSectionsInTableView:
[<timestamp etc>] Method no #3: tableView:didSelectRowAtIndexPath:
[<timestamp etc>] Method no #4: viewDidLoad

Post scriptum: Both @ThisDarkTao and @Pei got it right, as can be seen in my previous question documenting the visual parts, here.

Answer 1

You need to add UITableViewDelegate to the list of protocols in the interface file, like this: <UITableViewDataSource, UITableViewDelegate>

You also need all of the following delegate methods:

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return 1; // Number of rows
}

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

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    cell.textLabel.text = @"Test Cell";

    return cell;
}

In your xib/storyboard view, you also need to connect the tableview’s delegate and datasource connections to the viewcontroller.

If you want your cells to ‘do something’ when you tap them, you also need to implement the following delegate method:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    NSLog(@"Tapped cell %d",indexPath.row);     
}