Adding a sub-view appears to do nothing

Question

In my application, when the user clicks an infoButton, it should add another view to the screen at a specific location. I'm trying to achieve this behavior with the following method:

- (IBAction)showInfo1:(id)sender
  {
    UIView *myView1 = [[UIView alloc] initWithFrame:CGRectMake(25,25,50,20)];   
    [self.view addSubview:myView1]; 
  }

(I declared everything in the header file of my class.)

When I run the code and press the button, nothing appears to happen (I don't see the new view).

I also noticed that XCode is displaying the following warning:

Local declaration of 'myView1' hides instance variable.

Does anyone have any ideas?

Answer 1

How do you know nothing changes?

It looks like myView1 doesn't actually contain anything. Try setting the background color of myView1

- (IBAction) showInfo1: (id) sender
{
    UIView *myView1 = [[UIView alloc] initWithFrame:CGRectMake(25,25,50,20)];   
    myView1.backgroundColor = [UIColor redColor];
    [self.view addSubview: myView1]; 
}

To open it at a specific point you need to change the parameters in CGRectMake() for example

to open it at the very top left with a width of 50 and height of 20 you would do:

CGRectMake(0, 0, 50, 20)

Answer 2

"Local declaration of 'myView1' hides instance variable." message appears because you have declared in your class some property with the same name (even if the type is different).

If you put UIView *myView1 in your class definition, your method would look like

- (IBAction)showInfo1:(id)sender{
  myView1 = [[UIView alloc] initWithFrame:CGRectMake(25,25,50,20)];   
  [self.view addSubview:myView1]; 
}

Here comes more considerations: you must to release myView1 when you stop using it, avoid to be placed more than once, etc. but here we have the basic idea.

Finally, maybe your view is already added, but 'cause it doesn't contains anything yet, you don't notice it. Also you would like to check UIViewController to see if works better for you.