How can I change the background image view transparency image?

It is the code:

self.view.backgroundColor= [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"yourimage.png"]];

My "yourimage.png" have some space that is transparency. But it shows me it becomes black. How can I chang开发者_如何学编程e it to show the transparency instead of black color? thz.

Set the opaque property on the view to NO.