Load the view when app starts - iphone

Question

I want to create a app with only one view(TestViewController.h TestViewController.m). (no Tabbar, no Navigation Bar) Don't know why after i launch the app, the screen is totally black. It seems that the app did not load the view successfully? Since if the view is loaded, the screen should be white. Am I right or not?
Here's AppDelegate.h
#import <UIKit/UIKit.h>
#class TestViewController;
#interface AppDelegate : UIResponder <UIApplicationDelegate>
{
UIWindow *window;
TestViewController *testrViewController;
}
#property (strong, nonatomic) UIWindow *window;
#property (strong, nonatomic) TestViewController *testViewController;
#end
Here's AppDelegate.m
#import "AppDelegate.h"
#import "TestViewController.h"
#implementation AppDelegate
#synthesize window = window;
#synthesize testViewController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
[self.window addSubview:testViewController.view];
[self.window makeKeyAndVisible];
return YES;
}

Answer 1

It seems to me that you're not instatiating the class
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// add this line
testViewController = [[TestViewController alloc] init];
[.....]
}
Hope it helps

Answer 2

if you are creating it programmatically, then you should also instantiate window
UIWindow *aWindow = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.window = aWindow;
[aWindow release];
then your ViewController
testViewController = [[TestViewController alloc] init];
and then make it visible
[self.window addSubview:testViewController.view];
[self.window makeKeyAndVisible];

Answer 3

did you create .xib for testViewController. If not then you have to add a subview over your testViewController. and then try. I hope it will work.
UIView *testView=[[UIView alloc]initwithFrame:CGRectMake(0,0,320,480)];
[testViewController addsubview:testView];
[self.window addSubview:testViewController.view];
[self.window makeKeyAndVisible];