拋磚引玉
NSArray *arrViews = [[self.view subviews]copy];
layerBackground = [[UIView alloc]initWithFrame:self.view.frame];
[self.view addSubview:layerBackground];
for (int i=0; i<[arrViews count]; i++) {
[self.view bringSubviewToFront:[arrViews objectAtIndex:i]];
}
