Question

I am making an iPhone game where I have the user selecting what color they want their car to be in the game. To show which cars can be selected I have UIButtons with background images that are the various cars. To show which car is currently selected I have a button behind the current car color that has a background color of yellow. What I want to happen is that when you click on a car button the yellow button moves behind the button that was clicked. My code looks like:

    -(void)setPlayerCar:(UIButton *)newCar{
    //this code is being called when any of the buttons is clicked
    NSArray *carFiles = [NSArray arrayWithObjects:@"redCar.png",@"blueCar.png",@"greenCar.png",@"purpleCar.png",@"turquioseCar.png",@"yellowCar.png", nil];
    NSString *file = [carFiles objectAtIndex:newCar.tag];
    currentCarImage = file;
    CGRect frame;
    if(currentCarImage == @"redCar.png"){
        frame = CGRectMake(48, 78, 30, 30);
    }
    if(currentCarImage == @"blueCar.png"){
        frame = CGRectMake(83, 78, 30, 30);
    }
    if(currentCarImage == @"greenCar.png"){
        frame = CGRectMake(118, 78, 30, 30);
    }
    if(currentCarImage == @"purpleCar.png"){
        frame = CGRectMake(153, 78, 30, 30);
    }
    if(currentCarImage == @"turquioseCar.png"){
        frame = CGRectMake(188, 78, 30, 30);
    }
    if(currentCarImage == @"yellowCar.png"){
        frame = CGRectMake(223, 78, 30, 30);
    }
    for(UIButton *button in self.pauseScroll.subviews){
        if(button.backgroundColor == [UIColor yellowColor]){
           button.bounds = frame;
        }
        if(button.tag == newCar.tag){
           [self.pauseScroll bringSubviewToFront:button];
        }
    }
}

As far as I know this should move the yellow colored button over to the button that was selected. The problem is this doesn’t happen, when I debug I find that the correct button is being recognized and that frame is being given the right value and that the line: button.bounds = frame; is being executed but when I look at what is being displayed nothing has changed.

Answer 1

You should be changing the frame of the button and not the bounds. The bounds of a view describe a view’s location and size in its own coordinate space. The frame is the size and location in the superview’s coordinate space.

if (button.backgroundColor == [UIColor yellowColor]) {
    button.frame = frame;
}