how can i set part of the view appear at its child view

On the child view, I set the backgroundColor with a picture which have some transparent part.

[viewDown setBackgroundColor:[[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"background_down.png"]]];

The transparent part don't have the parent view's background, but the black color instea开发者_如何学God.

How can i do for this.

Thanks.

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Set the opaque property to NO.

viewDown.opaque = NO;