How to make Uibutton selected

I have a UIButton which remains selected when I select that button. Here is my code:

- (IBAction)cloudclick:(UIButton *)sender {
    UIImage *bgImage = [UIImage imageNamed:@"black_cloud.png"];
    UIButton *tmpButton = (UIButton *)[self.view viewWithTag:sender.tag];
    [tmpButton setBackgroundImage:bgImage forState:UIControlStateSelected];

} 

But it does not remain selected when I click the button. It changes the background but it does not remain as selected button.