Question

Is there something that I need to remember when using the windows-based template? Because I’m unclear as to why the tabs are showing up but nothing in the views are showing up.

Could you help? Because I’ve been searching through previous questions for a few hours now and I still haven’t found anything to clear this up.

AnotherMadeUpAppDelegate.h

#import <UIKit/UIKit.h>
#import "AnotherMadeUpViewController.h"

@interface AnotherMadeUpAppDelegate : NSObject <UIApplicationDelegate> {

}

@property (nonatomic, retain) IBOutlet UIWindow *window;

@end

AnotherMadeUpAppDelegate.m

#import "AnotherMadeUpAppDelegate.h"

@implementation AnotherMadeUpAppDelegate


@synthesize window=_window;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    UIViewController *vc1 = [[UIViewController alloc] init];
    UIViewController *vc2 = [[UIViewController alloc] init];
    AnotherMadeUpViewController *vc3 = [[AnotherMadeUpViewController alloc] init];

    UITabBarController *tbc = [[UITabBarController alloc] init];
    tbc.viewControllers = [NSArray arrayWithObjects:vc1, vc2, vc3, nil];
    [vc1 release];
    [vc2 release];
    [vc3 release];

    [self.window addSubview:tbc.view];
    [self.window makeKeyAndVisible];
    return YES;
}
...
@end

AnotherMadeUpViewController.h

#import <UIKit/UIKit.h>

@interface AnotherMadeUpViewController : UIViewController<UIScrollViewDelegate>
{

    IBOutlet UIPageControl *pageControl;
    IBOutlet UIScrollView *scroller;
    IBOutlet UILabel *label;
}

@property (nonatomic,retain)IBOutlet UIPageControl *pageControl;
@property (nonatomic,retain)IBOutlet UIScrollView *scroller;
@property (nonatomic,retain)IBOutlet UILabel *label;

-(IBAction)clickPageControl:(id)sender;

@end

AnotherMadeUpViewController.m

#import "AnotherMadeUpViewController.h"

@implementation AnotherMadeUpViewController
@synthesize pageControl,scroller,label;

-(IBAction)clickPageControl:(id)sender
{
    int page=pageControl.currentPage;
    CGRect frame=scroller.frame;
    frame.origin.x = frame.size.width * page;
    frame.origin.y = 0;
    [scroller scrollRectToVisible:frame animated:YES];
}

-(void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
    int page = scrollView.contentOffset.x/scrollView.frame.size.width;
    pageControl.currentPage=page;
}

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

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

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    scroller.pagingEnabled=YES;
    CGFloat labelOriginX = label.frame.origin.x;
    CGFloat labelOriginY = label.frame.origin.y;
    CGFloat scrollWidth = 0;
    int pageNumber = 0;
    for (int i=0; i<9; i++)
    {
        CGRect rect = label.frame;
        rect.size.height = label.frame.size.height;
        rect.size.width = label.frame.size.width;
        rect.origin.x = labelOriginX + scrollWidth;
        rect.origin.y = labelOriginY;
        label.frame = rect;
        label.text = [NSString stringWithFormat:@"%d", pageNumber];
        label.textColor = [UIColor redColor];
        [scroller addSubview:label];
        pageNumber++;
        scrollWidth += scroller.frame.size.width;
    }
    scroller.delegate=self;
    scroller.directionalLockEnabled=YES;
    scroller.showsHorizontalScrollIndicator=NO;
    scroller.showsVerticalScrollIndicator=NO;
    pageControl.numberOfPages=9;
    pageControl.currentPage=0;
    scroller.contentSize=CGSizeMake(pageControl.numberOfPages*self.view.frame.size.width, self.view.frame.size.height);
    [self.view addSubview:scroller];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    [label release];
    self.label = nil;
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

@end

Answer 1

Dissecting your viewDidLoad –

scroller = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width,self.view.frame.size.height)];

You seem to be creating a new scroll view instance here but you have declared it as an outlet. If you don’t have an outlet then remove the IBOutlet tag for scroller. If you do have one and want to use it then remove the above line. A shorter way of doing it would be,

scroller = [[UIScrollView alloc] initWithFrame:self.view.bounds];

Another thing is that you are creating 10 labels but assigning no frame. To show one of them each in different page,

int pageNumber = 0;
for (int i = 0; i < 10; i++)
{
    UILabel *label = [[UILabel alloc] init];
    [label sizeToFit];
    label.center = CGPointMake (((2 * i + 1) * self.view.frame.size.width) / 2, self.view.frame.size.height / 2);
    label.text = [NSString stringWithFormat:@"%d", pageNumber];

    [scroller addSubview:label];
    [label release];

    pageNumber++;
}

and later set the contentSize to show 10 pages,

scroller.contentSize = CGSizeMake(10 * self.view.frame.size.width, self.view.frame.size.height);