Question

I’m a newbie at iOS development and this is my first question on SO. My apologies if this is a dumb question.

I’m not using XIBs. My goal is to take a button and to move its position when the device rotates. My problem is that I can not find a way to update / refresh the button’s “frame” on the screen after a rotation takes place.

Here are the 04 files I’m using. I’ve read several other SO questions but I’m unable to fix this issue. Thank you all for any suggestions.

LV_AppDelegate.h

#import <UIKit/UIKit.h>
//
@class LV_ViewController;
//
@interface LV_AppDelegate : UIResponder <UIApplicationDelegate>
//
@property (strong, nonatomic) UIWindow *window;
//
@property (strong, nonatomic) LV_ViewController *viewController;
//
@end

LV_AppDelegate.m

#import "LV_AppDelegate.h"
#import "LV_ViewController.h"
//
@implementation LV_AppDelegate
//
@synthesize window = _window;
@synthesize viewController = _viewController;
//
- (void)dealloc
{
[_window release];
[_viewController release];
[super dealloc];
}
//
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
//
NSLog(@"Entering didFinishLaunchingWithOptions");
//
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.viewController = [[[LV_ViewController alloc] initWithNibName:@"LV_ViewController" bundle:nil] autorelease];
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;
}
//
- (void)applicationWillResignActive:(UIApplication *)application
{
}
//
- (void)applicationDidEnterBackground:(UIApplication *)application
{
}
//
- (void)applicationWillEnterForeground:(UIApplication *)application
{
}
//
- (void)applicationDidBecomeActive:(UIApplication *)application
{
}
//
- (void)applicationWillTerminate:(UIApplication *)application
{
}
//
@end

LV_ViewController.h

#import <UIKit/UIKit.h>
//
@interface LV_ViewController : UIViewController {
    UIButton *button_Narr_Places;
}
//
@property (nonatomic, retain) UIButton *button_Narr_Places;
//
@end

LV_ViewController.m

#import "LV_ViewController.h"
//
//
// - - - - - Open errors: - - - - -
/*
 a.) Local declaration of 'button_Narr_Places' hides instance variable.
 b.) If launched in Landscape, still thinks the device is in Portrait mode, and then 
 rotates to Landscape.
   Launched in Portrait
   Moved to Landscape
 c.) Can not see button once screen is rotated. How to refresh the button's "frame" position after it's updated by "willAnimateRotationToInterfaceOrientation"?
 */
// - - - - - 
@implementation LV_ViewController
//
@synthesize button_Narr_Places;
//
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}
//
- (void)viewDidLoad
{
    [super viewDidLoad];
}
//
- (void)loadView
{
    // - - Create the "view" canvas - -
    UIView *view = [[UIView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame];
    view.backgroundColor = [UIColor whiteColor];

    //
    // - - - - - Create a button - - - - -
    UIButton *button_Narr_Places    = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    //
    // - - - Adjust position based on INITIAL device orientation - - -
    UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
    //
    if (orientation == UIDeviceOrientationPortrait || orientation == UIDeviceOrientationPortraitUpsideDown) {
        NSLog(@"Launched in Portrait");
        button_Narr_Places.frame    = CGRectMake(10, 200, 100,  40);
    }
    else if (orientation == UIDeviceOrientationLandscapeRight || orientation == UIDeviceOrientationLandscapeLeft) {
        NSLog(@"Launched in Landscape");
        button_Narr_Places.frame    = CGRectMake(50, 400, 100,  40);
    }
    // - - - Add button's title, color, selector - - -
    [button_Narr_Places setTitle:@"Places Lived" forState:UIControlStateNormal];
    button_Narr_Places.backgroundColor = [UIColor clearColor];
    button_Narr_Places.tag = 2000;
    [button_Narr_Places addTarget:self action:@selector(method_Narr_Places:) 
                 forControlEvents:UIControlEventTouchUpInside];
    //
    [view addSubview:button_Narr_Places];
    //

    // -- Create a "label" view:
    CGRect frame = CGRectMake(10, 85, 300, 20);
    UILabel *label = [[UILabel alloc] initWithFrame:frame];
    label.textAlignment = UITextAlignmentCenter;
    label.backgroundColor = [UIColor clearColor];
    label.font = [UIFont fontWithName:@"Verdana" size:20];
    label.text = @"Test ViewController.";
    label.tag = 1000;
    //
    [view addSubview:label];
    [label release];
    self.view = view;
}
//
// - - - - - Method called by button above - - - - -
- (IBAction)method_Narr_Places:(id)sender
{
    NSLog(@"Entering method_Narr_Places");
}
//
-(void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation) interfaceOrientation duration:(NSTimeInterval)duration 
{       
    UIInterfaceOrientation orientation = [[UIApplication sharedApplication] statusBarOrientation];
    if (orientation == UIDeviceOrientationPortrait) {
        NSLog(@"Moved to Portrait");
        //
        // [button_Narr_Places setFrame:CGRectMake( 10, 778, 100,  40)];
        button_Narr_Places.frame  = CGRectMake( 10, 200, 100,  40);
    }
    else if (orientation == UIDeviceOrientationPortraitUpsideDown) {
        NSLog(@"Moved to Portrait UpsideDown");
    }
    //
    else if (orientation == UIDeviceOrientationLandscapeRight || orientation == UIDeviceOrientationLandscapeLeft) {
        NSLog(@"Moved to Landscape");
        //
        // [button_Narr_Places setFrame:CGRectMake(778, 100, 100,  40)];
        button_Narr_Places.frame  = CGRectMake(50, 400, 100,  40);
    }

}
//
// - - - - - Boilerplate methods below - - - - -
//
- (void)viewDidUnload
{
    [super viewDidUnload];
}
//
- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
}
//
- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];
}
//
- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
}
//
- (void)viewDidDisappear:(BOOL)animated
{
    [super viewDidDisappear:animated];
}
//
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}
//
@end

Answer 1

In your LV_ViewController.m - loadView function, you are declaring the (local) variable for the button like this:

UIButton *button_Narr_Places    = [UIButton buttonWithType:UIButtonTypeRoundedRect];

This creates a temporary local copy of the button (which “hides” the global property so that you can’t access it in this function) and then throws it away at the end of the function. If you want to be able to reference it later (like in willAnimateRotationToInterfaceOrientation) you need to use the property that you defined in your header file:

button_Narr_Places    = [UIButton buttonWithType:UIButtonTypeRoundedRect];

or even better:

self.button_Narr_Places    = [UIButton buttonWithType:UIButtonTypeRoundedRect];

Note that unless you have a reason otherwise, you should be using the self. notation to access the ivar through it’s accessor instead of directly.