Multiple Views in Xcode 4.2 - objective-c

Question

I'm having a lot of trouble finding a tutorial for implementing multiple views in Xcode 4.2 without storyboard, this is for a class so I can't use storyboard yet. I'm just trying to have a 2nd view with a UIPicker come up when a button is clicked in the main view, I just can't find one for this version of Xcode and it's different enough from the older versions to confuse me.
Any help appreciated if someone can give me a quick description of what I need to do this or a newer tutorial I'd appreciate it :)

Answer 1

I think you should read the UIView Programming Guide to get a good handle on how UIViews work exactly. I find nibs/storyboard are really great at confusing new iOS developers.
In essence, a UIViewController has 1 view which you set in the viewDidLoad or loadView method by using the [self setView:someUIView]. You add more stuff to the screen by adding UIViews as a subview of the viewcontroller's "Main" view. For example
-(void)loadView {
// Create a view for you view controller
UIView *mainView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
[self setView:mainView];
// Now we have a view taking up the whole screen and we can add stuff to it
// Let's try a button, a UIButton is a subview of UIView
UIButton *newButton = [[UIButton buttonWithType:UIButtonTypeRoundedRect];
// We need to set a frame for any view we add so that we specify where it should
// be located and how big it should be!
[newButton setFrame:CGRectMake(x,y,width,height)];
// Now let's add it to our view controller's view
[self.view addSubview:newButton];
// You can do the same with any UIView subclasses you make!
MyView *myView = [[MyView alloc] init];
[myView setFrame:CGRectMake(x,y,width,height)];
[self.view addSubview:myView];
}
Now here we have our viewController who'se view is just a plain UIView which in turn has 2 subviews; newButton and myView. Since we created the MyView class, maybe it contains subviews as well! Let's take a look at what a UIView subclass could look like:
// Here is the init method for our UIView subclass
- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
// Let's add a button to our view
UIButton *newButton2 = [[UIButton buttonWithType:UIButtonTypeRoundedRect];
// Of course, the frame is in reference to this view
[newButton2 setFrame:CGRectMake(x,y,width,height)];
// We add just using self NOT self.view because here, we are the view!
[self addSubview:newButton2];
}
return self;
}
So in this example we would have a view controller who'se view now contains 2 button! But the view structure is a tree:
mainView
/ \
newButton myView
\
newButton2
Let me know if you have any other questions!
Matt