Question

i’m studying iOS programming. but i have a problem, which is opaque.

now assume. i have two image views.

when i write code, it works. code is here.

UIImageView *imageView1 = [[UIImageView alloc] initWithImage:@"something1"];
UIImageView *imageView2 = [[UIImageView alloc] initWithImage:@"something2"];
imageView2.opaque = NO;
[controller addSubView:imageView1];
[controller addSubView:imageView2];

now, imageView2 is on the imageView1. but imageView2’s property opaque set to NO.

so i can see imageView1 only. ok. that’s what i want.

but i want to do more easily. so i use interface builder.

i have two image views. one is wire up IBOutlet ImageView *imageView1

and another one is IBOutlet ImageView *imageView2.

and i set the imageView2’s inspector. and uncheck opaque.

and i build it. so i think it’s same effect as code above.

but imageView2 is on the imageView1.

it’s not disappear.

why is that?

why code can work but interface builder not?

Answer 1

UIView’s opaque property is used for determining whether the view can optimize compositing operations. You should be setting the alpha property.