Switching ViewControllers, but nothing happens? - iphone

Question

I want to put the code of switching ViewControllers to a single class, which named SwitchController. But nothing happens.
Here is the code:
//AppDelegate.m
-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.window.backgroundColor = [UIColor whiteColor];
RootViewController *root = [[RootViewController alloc] init];
[self.window setRootViewController:root];
[self.window makeKeyAndVisible];
return YES;
}
//SwitchController.h
#interface SwitchController : NSObject
#property (strong,nonatomic) RootViewController *rootViewController;
+(SwitchController *)sharedInstance;
-(void)requestToSwitchViewController:(NSInteger)tag;
#end
//SwitchController.m
#import "SwitchController.h"
#import "FirstViewController.h"
#import "SecondViewController.h"
#implementation SwitchController
#synthesize rootViewController = _rootViewController;
-(id)init
{
self = [super init];
if (self == nil)
{
_rootViewController = [[RootViewController alloc] init];
}
return self;
}
+(SwitchController *)sharedInstance
{
static SwitchController *sharedSingleton = nil;
#synchronized([SwitchController class])
{
if(sharedSingleton == nil)
{
sharedSingleton = [[self alloc] init];
}
}
return sharedSingleton;
}
-(void)requestToSwitchViewController:(NSInteger)tag
{
switch (tag)
{
case 1:
{
FirstViewController *first = [[FirstViewController alloc] init];
[self.rootViewController presentViewController:first animated:YES completion:nil];
}
break;
......... //Do something else
default:
break;
}
}
#end
//This is the self.window.rootViewController------RootViewController.m
//In this ViewController's view, there is a button, and on press, it will do the following thing
- (IBAction)pressed:(id)sender
{
[[SwitchController sharedInstance] requestToSwitchViewController:[(UIButton *)sender tag]];
}
So, is there anything wrong with my code?
Why does nothing happens when I press the button?

Answer 1

There may be several issues..
1) Check whether your button outlet is correctly connected to this method -(IBAction)pressed:(id)sender;
2)Add this line after #synthesize in SwitchController.m
static SwitchController *sharedSingleton = nil;
3)change your method like this
+(SwitchController *)sharedInstance
{
if(sharedSingleton == nil)
{
sharedSingleton = [[self allocWithZone:NULL] init];
}
return sharedSingleton;
}
4) Remove this line from the -id(init) method
// You do not need to re-initialize the root view controller
_rootViewController = [[RootViewController alloc] init];
5) Check whether the button is valid. Before calling this method requestToSwitchViewController: check what it logs
UPDATE:
Try like this: (For this, you need to create a property for navigation controller in your appDelegate and synthesize it)
switch (tag)
{
case 1:
{
FirstViewController *first = [[FirstViewController alloc] init];
appDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
[appDelegate.navigationController presentViewController:first animated:YES completion:nil];
}
.....
.........
}

Answer 2

I guess you're just defining the viewController, you need to define the View too. they're different things.