For loop ignoring isKindOfClass for uibuttons in scrollview - ios

Question

I have code that creates, adds and tags unbuttons in a uiview which is itself in a uiscrollview. At a certain point I try to change (background color and image) some of the unbuttons with certain tags . The problem is if I choose the first button with tag 0 the for loop bombs out for the image change because either uiscrollview or the uiview do not have that method available. But I am trying to only target the unbuttons within the view (all synched up). If I pick any other buttons it works as expected. I could offset the tag from 0 to one instead but I want to know why my for loop does not work.
for (int i=0; i<[devicesArray count]; i++) {
NSLog(#"red %i", i);
for (UIView *subview in [uiv_ButtonsView subviews]) {
if([subview isKindOfClass:[UIButton class]]) {
int number = [[devicesArray objectAtIndex:i] intValue];
subview.alpha=1.0;
[[subview viewWithTag:number] setBackgroundColor:[UIColor redColor]];
UIButton *btttn = (UIButton *)[subview viewWithTag:number];
[btttn setBackgroundImage:nil forState:UIControlStateNormal];
}
}
}
Thanks - this is now working code:
for (int i=0; i<[devicesArray count]; i++) {
int number = [[devicesArray objectAtIndex:i] intValue];
[[uiv_Quilt viewWithTag:number] setBackgroundColor:[UIColor redColor]];
[[uiv_Quilt viewWithTag:number] setBackgroundImage:nil forState:UIControlStateNormal];
}

Answer 1

for (UIView *subview in [uiv_ButtonsView subviews]) {
subView is a subview of uiv_ButtonsView
if([subview isKindOfClass:[UIButton class]]) {
subView is a UIButton
[[subview viewWithTag:number] setBackgroundColor:[UIColor redColor]];
Hmmm. Now you're getting a subview of the UIButton, with tag 0 - this is the default tag for all views. You're in the private view hierarchy of the UIButton here, we've no idea what this is.
UIButton *btttn = (UIButton *)[subview viewWithTag:number];
Same again - you've told the compiler that you are getting a button back from this call, but you won't be. subView is already a button, buttons don't have other buttons as subviews.
[btttn setBackgroundImage:nil forState:UIControlStateNormal];
So this line of code won't work.
I don't see why you either do all your operations on subView, or use [uiv_ButtonsView viewWithTag:xx] to get your button. In the latter case, you will need to start your tags at 1, since all views have a default tag of 0.

Answer 2

The [subview viewWithTag:number] doesn't make sense to me (your button, subview, presumably doesn't have further subviews). And the iteration through your devicesArray with a nested iteration through the uiv_ButtonsView doesn't makes sense either. If you're using tags, you shouldn't need to iterate through your uiv_ButtonsView's subviews, but rather you could have used [uiv_ButtonsView viewWithTag:number].