implementing a cyclic UITableView

Question

What is the best way to implement a cyclic UITableView where instead of showing white space when the user scrolls up to the table\'s bounds, it simply wraps round cyclically

Answer 1

I have seen this behavior a couple of times but not in a UITableView it was a UIPickerView. The code is quite simple and probably convertible to a UITableView....

The code for ciclic UIPickerView

RollerViewController.h

@interface RollerViewController : UIViewController {
    UIPickerView *picker;
}    
@end

RollerViewController.m

#import "RollerViewController.h"

@implementation RollerViewController

#define MAX_ROLL 100
#define ROWS_COUNT 10

#pragma mark -
#pragma mark Helpers

- (void) infinitePickerViewDidSelectRow:(NSInteger)row inComponent:(NSInteger)component{
    NSUInteger base10 = (MAX_ROLL/2) - (MAX_ROLL/2)%ROWS_COUNT;
    [picker selectRow:row%ROWS_COUNT+base10 inComponent:component animated:FALSE];
}

#pragma mark -
#pragma mark UIPickerView dataSource delegate methods

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)thePickerView {
    return 3;
}
- (NSInteger)pickerView:(UIPickerView *)thePickerView numberOfRowsInComponent:(NSInteger)component {
    return MAX_ROLL;
}
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component{
    return (CGFloat)40;
}
- (void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    [self infinitePickerViewDidSelectRow:row inComponent:component];
}

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component{
    return (CGFloat) 50;
}
- (UIView *)pickerView:(UIPickerView *)thePickerView viewForRow:(NSInteger)row 
          forComponent:(NSInteger)component reusingView:(UIView *)rview {

    UILabel *retval = (UILabel *)rview;
    if (!retval) {
        retval= [[[UILabel alloc] initWithFrame:CGRectMake(5,5,40,30) ] autorelease];
    }

    retval.text = [NSString stringWithFormat:@"%d", row%ROWS_COUNT];
    retval.font = [UIFont systemFontOfSize:25];
    retval.textAlignment = UITextAlignmentCenter;
    retval.backgroundColor = [UIColor clearColor];
    return retval;
}

#pragma mark overides

- (void)viewDidLoad {
    [super viewDidLoad];
    picker = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 0, 320, 280)];
    picker.delegate = self;
    [self.view addSubview:picker];

}
- (void) viewDidAppear:(BOOL)animated{
    [super viewDidAppear:animated];

    [self infinitePickerViewDidSelectRow:arc4random()%MAX_ROLL inComponent:0];
    [self infinitePickerViewDidSelectRow:arc4random()%MAX_ROLL inComponent:1];
    [self infinitePickerViewDidSelectRow:arc4random()%MAX_ROLL inComponent:2];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}

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

- (void)dealloc {
    [picker release];
    [super dealloc];
}

@end