iPhone SDK: subvistas no transparentes en vista transparente

Question

tengo una vista secundaria que se ha añadido a mi UIView. La idea es que la subvista sea un panel flotante con uibutones. La subvista recibe un alfa de 0,2, ya que el usuario necesita poder ver qué hay detrás.

El problema es que cuando agrego uibuttons a la subvista, heredan el alfa de la subvista (quiero que los botones sean no transparentes y tengan un alfa de 1.0). Intenté resolver este problema iterando a través de los uibutones y restableciendo su alfa a 1.0 sin éxito. Soluciones?

// Create the subview and add it to the view 
    topHoverView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 50)]; 
    topHoverView.backgroundColor = [UIColor blackColor]; 
    [topHoverView setAlpha:0.2]; 
    [self.view addSubview:topHoverView]; 

    // Add button 1 
    button1 = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
    [button1 setFrame:CGRectMake(20, 10, 80, 30)]; 
    [button1 setTitle:@"New" forState:UIControlStateNormal]; 
    [button1 addTarget:self action:@selector(button1Action:) forControlEvents:UIControlEventTouchUpInside]; 
    [topHoverView addSubview:button1]; 

    // Add button 2 
    button2 = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
    [button2 setFrame:CGRectMake(120, 10, 80, 30)]; 
    [button2 setTitle:@"Clear" forState:UIControlStateNormal]; 
    [button2 addTarget:self action:@selector(button2Action:) forControlEvents:UIControlEventTouchUpInside]; 
    [topHoverView addSubview:button2]; 

    // Add button 3 
    button3 = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
    [button3 setFrame:CGRectMake(220, 10, 80, 30)]; 
    [button3 setTitle:@"Delete" forState:UIControlStateNormal]; 
    [button3 addTarget:self action:@selector(button3Action:) forControlEvents:UIControlEventTouchUpInside]; 
    [topHoverView addSubview:d button3]; 

    // Attempt to iterate through the subviews (buttons) to set their transparency back to 1.0 
    for (UIView *subView in topHoverView.subviews) { 
     subView.alpha = 1.0; 
    } 

Answer 1

Debe crear topHoverView con alpha 1.0 y un color de fondo transparente. A continuación, añadir una vista secundaria con un fondo negro que cubre la visión completa con alfa 0,2 y luego añadir los botones para topHoverView:

// Create the subview and add it to the view 
topHoverView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 50)]; 
topHoverView.backgroundColor = [UIColor transparentColor]; 
[topHoverView setAlpha:1.0]; 
[self.view addSubview:topHoverView]; 

canvasView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 50)]; 
canvasView.backgroundColor = [UIColor blackColor]; 
[canvasViewView setAlpha:0.2]; 
[topHoverView.view addSubview:canvasView]; 

// Add button 1 
button1 = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
[button1 setFrame:CGRectMake(20, 10, 80, 30)]; 
[button1 setTitle:@"New" forState:UIControlStateNormal]; 
[button1 addTarget:self action:@selector(button1Action:) forControlEvents:UIControlEventTouchUpInside]; 
[topHoverView addSubview:button1]; 

// Add button 2 
button2 = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
[button2 setFrame:CGRectMake(120, 10, 80, 30)]; 
[button2 setTitle:@"Clear" forState:UIControlStateNormal]; 
[button2 addTarget:self action:@selector(button2Action:) forControlEvents:UIControlEventTouchUpInside]; 
[topHoverView addSubview:button2]; 

// Add button 3 
button3 = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
[button3 setFrame:CGRectMake(220, 10, 80, 30)]; 
[button3 setTitle:@"Delete" forState:UIControlStateNormal]; 
[button3 addTarget:self action:@selector(button3Action:) forControlEvents:UIControlEventTouchUpInside]; 
[topHoverView addSubview:d button3]; 

// Attempt to iterate through the subviews (buttons) to set their transparency back to 1.0 
for (UIView *subView in topHoverView.subviews) { 
    subView.alpha = 1.0; 
} 

Answer 2

En lugar de

topHoverView.backgroundColor = [UIColor transparentColor]; 

, el siguiente código es correcto.

topHoverView.backgroundColor = [UIColor clearColor];