Having problem with view switching from a subview...

Question

Hi Everyone,

Maybe this is a silly question but I'm having a problem with switching the view in a subview. Let me explain the code structure:

I have these class files:

/classes/MySoftwareAppDelegate.h
/classes/MySoftwareAppDelegate.m
/classes/ViewController.h
/classes/ViewController.m
/classes/LoginController.h
/classes/LoginController.m
/classes/CustomersController.h
/classes/CustomersController.m

I have these views:

/resources/MainWindow.xib
/resources/Login.xib
/resources/Customers.xib

In the AppDelegate, I have successfully inserted the sub view "Login" and it's displayed whenever the app starts.

In the login view, I enter my username and password and then click the "Login" button. When this button is clicked, an IBAction is triggered. In this IBAction, I want to change the current subview with the Customers.

Here's the code I have used:

MySoftwareAppDelegate.h

#import <UIKit/UIKit.h>

@class ViewController;

@interface MySoftwareAppDelegate : NSObject <UIApplicationDelegate> {
    UIWindow *window;
 ViewController *viewController;
}

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

@end

MySoftwareAppDelegate.m

#import "MySoftwareAppDelegate.h"
#import "ViewController.h"

@implementation MySoftwareAppDelegate

@synthesize window;
@synthesize viewController;


- (void)applicationDidFinishLaunching:(UIApplication *)application {    

    // Override point for customization after application launch
 [window addSubview:viewController.view];
    [window makeKeyAndVisible];
}


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


@end

ViewController.h

#import <UIKit/UIKit.h>

@class LoginController;

@interface ViewController : UIViewController {
 LoginController *loginController;
}

@property (nonatomic, retain) LoginController *loginController;

@end

ViewController.m

#import "ViewController.h"
#import "LoginController.h"

@implementation ViewController

@synthesize loginController;

- (void)viewDidLoad {
 LoginController *tmpViewController = [[LoginController alloc] initWithNibName:@"Login" bundle:nil];

 self.loginController = tmpViewController;
 [self.view insertSubview:loginController.view atIndex:0];

 [tmpViewController release];

    [super viewDidLoad];
}

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

 if (self.loginController.view.superview == nil) {
  self.loginController = nil;
 }

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

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


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

@end

LoginController.h

#import <UIKit/UIKit.h>

@class CustomersController;

@interface LoginController : UIViewController {
 UIButton *loginButton;
 UITextField *usernameTextField;
 UITextField *passwordTextField;
 NSMutableString *available_credits;
 NSString *current_xml_element;
 CustomersController *customersController;
}

@property (nonatomic, retain) IBOutlet UIButton *loginButton;
@property (nonatomic, retain) IBOutlet UITextField *usernameTextField;
@property (nonatomic, retain) IBOutlet UITextField *passwordTextField;
@property (nonatomic, retain) NSMutableString *available_credits;
@property (nonatomic, retain) NSString *current_xml_element;
@property (nonatomic, retain) CustomersController *customersController;

-(IBAction)textFieldDoneEditing:(id)sender;
-(IBAction)backgroundTap:(id)sender;
-(IBAction)loginToAccount:(id)sender;

@end

LoginController.m

#import "LoginController.h"
#import "CustomersController.h"

@implementation LoginController

@synthesize loginButton;
@synthesize usernameTextField;
@synthesize passwordTextField;
@synthesize customersController;

- (void)viewDidLoad {
 UIImage *buttonImageNormal = [UIImage imageNamed:@"whiteButton.png"];
 UIImage *stretchableButtonImageNormal = [buttonImageNormal stretchableImageWithLeftCapWidth:12 topCapHeight:0];
 UIImage *buttonImagePressed = [UIImage imageNamed:@"blueButton.png"];
 UIImage *stretchableButtonImagePressed = [buttonImagePressed stretchableImageWithLeftCapWidth:12 topCapHeight:0]; 

 [loginButton setBackgroundImage:stretchableButtonImageNormal forState:UIControlStateNormal];
 [loginButton setBackgroundImage:stretchableButtonImagePressed forState:UIControlStateHighlighted];
}

- (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.
}

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

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

-(IBAction)textFieldDoneEditing:(id)sender {
 [sender resignFirstResponder];
}

-(IBAction)backgroundTap:(id)sender {
 [usernameTextField resignFirstResponder];
 [passwordTextField resignFirstResponder];
}

-(IBAction)loginToAccount:(id)sender {

 // bla bla bla... Login check process is done here

 CustomersController *tmpViewController = [[CustomersController alloc] initWithNibName:@"Customers" bundle:nil];
 self.customersController = tmpViewController;

 [self.view removeFromSuperview];

 [tmpViewController release];

}

@end

As you can see above, in LoginController.m's loginToAccount method, I am checking the login info and then setting the new view controller for the "customers" sub-view.

Then I am removing the current "Login" subview from the super view but don't know how to add the new "Customers" sub view.

In MainWindow.xib, I have one view controller which is linked to ViewController class and it's the root contoller.

Any help is appreciated. Because I am new to Objective-C and iPhone programming, please do your best to explain considering a novice programmer :)

Thanks again.

Answer 1

You are not adding any views to the view hierarchy, just removing the login view controller. If you want to add your customer view to the view hierarchy you should use:

CustomersController *tmpViewController = [[CustomersController alloc] initWithNibName:@"Customers" bundle:nil];
self.customersController = tmpViewController;
[self presentModalViewController:tmpViewController]

The above method will make sure that the viewWillLoad, didLoad etc are called on the account view controller. It will also take care of removing and adding the correct views to the view hierarchy for you.